MPO Polarity and Base-8 vs Base-12: Getting 40G to 800G Right

October 5, 2026

A 100G switch port came up dark on install day. Both trunks tested clean on loss, every connector passed visual inspection, and the transceivers were swapped twice before anyone checked the patch cords: Type B cords on both ends of a Type A trunk. Nothing was faulty. Nothing was ever going to work.

Polarity is the failure that measurement does not catch, because the light arrives in perfect condition — at the wrong fiber.

MPO Basics: Keys, Pins and Position 1

Every MPO connector has a key on one side of the body and a white dot on the side marking Position 1. Looking at the end face, Position 1 is on the far left and Position 12 on the far right. On a 24-fiber MPO, the top row runs Positions 1 to 12 and the bottom row 13 to 24.

Two orientations exist: key up, with the key at the top, and key down. Adapters come in two mating styles, key-up-to-key-down or key-up-to-key-up, and the polarity method decides which.

Gender is separate from polarity and just as absolute. A male MPO has two alignment pins; a female MPO has two alignment holes that receive them. Connection is male-to-female only, because the pins are what align the fibers precisely enough to keep loss low.

That has a practical consequence at the equipment end. Active equipment typically uses male MPO interfaces, so any cable plugged directly into a transceiver or switch port must be female — otherwise the cable’s pins meet the transceiver’s pins, and the transceiver loses.

Method A, Method B and Method C

TIA-568 defines three polarity methods. They differ in cable orientation, connector orientation and fiber assignment, and the naming between sources is not consistent — so it is worth reading both the name and the mechanism.

Method	What it does to position mapping	Connector / adapter arrangement
A	Straight-through: Position 1 arrives at Position 1	Key-up on one end, key-down on the other; Type A adapters mate key-up to key-down
B	Reversed: Position 1 arrives at Position 12	Key-up connectors on both ends; Type B adapters mate key-up to key-up
C	Pair flip: Position 1 arrives at Position 2, Position 2 at Position 1, repeated throughout	Cross-over trunk; not suitable for parallel optics

Under Method A, a Type A straight-through trunk is used with a Type A patch cord on one end and a Type B patch cord on the other. TIA allows only one Type B patch cord in a link. The Type B cord is key-up to key-up, which produces the Position 1 to Position 12 flip the transceivers require.

Under Method B the flip happens in the trunk instead, so the patch cords are uniform: a Type B reversed trunk with Type B adapters and Type B patch cords at both ends gives a key-up-to-key-up arrangement throughout the channel.

Method C flips adjacent fiber pairs. It works for duplex but is unsuitable for parallel optics, and the arithmetic explains why: Positions 1 and 2 are paired, as are 11 and 12, leaving those four unusable and reducing a 12-fiber MPO to 8 usable positions — not enough for 100GbE. Type C trunks and patch cords are also not readily available.

Which Method to Use, and Why Sources Differ

Two reputable sources emphasize different recommendations, and both are defensible.

Fluke Networks recommends Method B for parallel optics for an operational reason: since the same patch cord type is used throughout the channel, uncertainty about cord selection is eliminated. A technician cannot fit the wrong cord at one end because there is only one cord type.

Senko describes Method A as the simplest design to install and maintain, because MPO connector orientation stays consistent throughout the network — the flip lives in the patch cords rather than the trunk. The trade-off is two different duplex patch cords at the transceiver and receiver ends, which Senko addresses by allocating one cord type to a fixed terminal so it cannot be installed wrongly.

The reconciliation is that the two optimize for different people. Method B optimizes for the installer who cannot get it wrong. Method A optimizes for a plant where connector orientation is standardized and cord types are managed by position. Whichever you choose, choose it once, in design, and write it down.

Modified Method B: Why APC Changes the Adapter

This is the detail that catches out people who learned Method B on multimode and then applied it to single-mode.

All single-mode MPO connectors use angled physical contact (APC) end faces with an 8-degree angle to improve reflectance, and APC multimode MPO connectors are now common at 400G and 800G, where back reflections matter more.

Mating APC connectors requires a key-up-to-key-down configuration for the end faces to align, but standard Method B is key-up-to-key-up. The industry resolves this by using Type A adapters (key-up to key-down) with Type B cables and Type B patch cords at both ends — "Modified Method B." With Type A adapters, the orientation of the Type B cable changes, delivering the alignment angled end faces require.

The related trap is material: polarity cannot be changed on APC connectors, because the angled end face must stay in a fixed orientation. Field-changeable polarity, where it exists, is a UPC multimode capability only.

Base-8, Base-12 and Base-16

The "base" number is the fiber count of the MPO ferrule, and it decides how cleanly an assembly maps onto common optics.

Base	Fibers	Best for	The catch
Base-8	8	4-lane optics: 40G/100G SR4, 400G DR4	100 percent fiber utilization — the default for new builds
Base-12	12	Existing Base-12 structured cabling	Four fibers go dark on 4-lane optics
Base-16	16	8-lane optics: 400G/800G SR8, AI and GPU fabrics	Keying conventions differ from Base-12 — never mate by force
Base-24	24	Backbone aggregation, legacy SR10	Most complex polarity management

Base-8 uses the same form factor as Base-12 with the four center fibers removed. That is the whole idea: early 40GBASE-SR4 and 100GBASE-SR4 links used only 8 fibers — 4 transmitting and 4 receiving — so deploying them over 12-fiber MPO wasted the center four. Removing them produced a connector that maps 1:1 onto 4-lane optics.

Existing Base-12 plants are not stranded. Conversion patch cords or cassettes break out two Base-12 MPOs (24 fibers) to three Base-8 connectors (24 fibers), which is how an installed duplex backbone becomes a parallel-optics plant without stranding fiber.

Base-12 remains common for consolidating duplex backbone cabling, and it is now rarely deployed for parallel optics. Base-16 is the matching choice for 400G and 800G SR8, which run 8 lanes.

Fibers per Transceiver

Getting the fiber count wrong is the second most expensive ordering mistake after polarity, because pre-terminated MPO assemblies are made to order.

Transceiver	Lanes	Fibers used	Typical assembly
40G-SR4 (QSFP+)	4 × 10G	8 (on MPO-12: 8 active, 4 dark)	MPO-8/12 → 4× LC duplex
100G-SR4 (QSFP28)	4 × 25G	8	MPO-8/12 → 4× LC duplex
400G-DR4 (QSFP-DD)	4 × 100G	8, single-mode APC	MPO-8/12 → 4× LC duplex
400G-SR8 (QSFP-DD)	8 × 50G PAM4	16, multimode UPC	MPO-16 → 8× LC duplex
800G-SR8 (OSFP/QSFP-DD)	8 × 100G PAM4	16, multimode UPC	MPO-16 → 8× LC duplex
100G-SR10 (legacy CFP/CPAK)	10 × 10G	20 (on MPO-24: 20 active, 4 dark)	MPO-24 → 10× LC duplex

The 800G generation continues on the same principle. IEEE 802.3dj will support 800 Gig over 8 single-mode fibers — 4 transmitting and 4 receiving at 200 Gb/s.

One interface family cannot be broken out at all. WDM interfaces such as 400G-FR4, 400G-LR4 and 800G-FR4 carry every lane on a single duplex pair, so there are no parallel lanes to fan out.

Two specification points follow. Polishing must match the mode: UPC for multimode, APC for single-mode parallel optics such as 400G-DR4 and 800G-DR8, and mixing the two damages end faces. And the default for a transceiver breakout is Type B polarity with a female MPO, because most QSFP, QSFP-DD and OSFP ports are pinned.

How to Specify, Order and Test

Decide polarity in design, not in the field. Pre-terminated MPO assemblies and jumpers are normally made to order and are often nonreturnable, so a polarity mistake discovered during installation converts into lead time and cost rather than a return.

State gender explicitly on the purchase order. "Female MPO to 4× LC duplex" is a specification. "MPO to LC breakout" is not.

Match the base to the optic. Base-8 for 4-lane optics, Base-16 for 8-lane SR8. Where the plant is already Base-12, plan the conversion rather than ordering Base-12 assemblies for 4-lane links and accepting four dark fibers.

Confirm the fiber mode against the transceiver, not against preference. On the same optic, OM4 buys reach over OM3 — 40G-SR4 runs 100 m on OM3 versus 150 m on OM4, and 100G-SR4 runs 70 m versus 100 m. OM5 adds value only for SWDM links. OS2 single-mode uses G.652.D fiber with APC polish.

Test polarity directly, with an instrument that reads all fibers. Loss testing passes a polarity error, because the light arrives cleanly at the wrong position. An MPO-capable tester scans all 8 or 12 fibers, verifies position mapping and reports insertion loss per fiber — which is also how a mis-ordered patch cord is caught before it costs a truck roll.

Our fiber optic cable range covers single-mode and multimode constructions, and communication cable covers the copper side of the same data center build. How Ethernet cables work explains the transmission principles underneath, our patch cord range is assembled and tested as complete units, and every test and inspection parameter we publish is listed by measurement. If an MPO link is dark and the trunks have already tested clean, send us the configuration — trunk type, adapter type, cord types and fiber count are usually enough to find it.

Frequently Asked Questions

What is the difference between MPO and MTP?

MTP is a specific improved MPO connector design rather than a different interface standard. Both mate with each other, and the polarity rules in this article apply to both.

Which polarity method should I use for 100G and 400G?

Method B, or Modified Method B where APC end faces are involved. Method B keeps a single patch cord type throughout the channel, which removes the possibility of installing the wrong cord. Method C is not suitable for parallel optics.

Why does my link test clean but stay dark?

Because loss testing measures whether light arrives, not where it arrives. A polarity error delivers full power to the wrong fiber, so every loss measurement passes while the transceivers never see each other. Test position mapping, not just loss.

Can I change MPO polarity in the field?

On UPC multimode connectors, yes — some designs allow the key position to be changed between key up and key down with a tool or by rotating an interchangeable housing. On APC connectors, no, because the angled end face must stay in a fixed orientation.

Can a 400G-FR4 port be broken out with an MPO cable?

No. FR4 and LR4 interfaces multiplex all lanes onto one duplex pair, so there are no parallel lanes to fan out.

The Short Version

Polarity decides which fiber the light lands on, and it is the one fiber failure that loss testing cannot see. Position 1 on an MPO has to arrive at the right position at the far end, and three TIA-568 methods get it there differently: Method A flips in the patch cords, Method B flips in the trunk, Method C flips fiber pairs and is unsuitable for parallel optics.

Method B is recommended for parallel optics because one patch cord type is used throughout, so it cannot be installed wrongly. Where APC end faces are involved — all single-mode, and increasingly multimode at 400G and 800G — the 8-degree angle forces a key-up-to-key-down mating, which is achieved with Type A adapters in what the industry calls Modified Method B.

Base-8 has become the default for new builds because it maps 1:1 onto 4-lane optics, with Base-12 now mainly a duplex backbone consolidation choice and Base-16 matching 8-lane 400G and 800G SR8. Gender is absolute: male to female only, and equipment ports are usually pinned, so cables landing on them must be female.

Decide polarity and gender in design, put both on the purchase order, and test position mapping rather than loss alone.

Sources

Fluke Networks — Getting 12- and 8-Fiber MPO Polarity Right, covering the definition of fiber optic polarity as ensuring a fiber link transmit signal matches its corresponding receiver at the other end, the statement that this correspondence is a common point of confusion especially with 12-fiber multi-fiber MPO links, the description of MPO connectors coming in multimode and single-mode versions with various fiber counts and either male with pins or female without pins, that the pins ensure precise alignment when connectors are mated, that active equipment typically uses male MPO interfaces with pins so any MPO cable plugged directly into the equipment must be female without pins to prevent damage to the transceiver, that MPO connectors feature a key on the top side and a white dot on the side to indicate Position 1, the history of the 12-fiber MPO connector being a popular choice for consolidating duplex backbone cabling in the data center, the emergence of parallel-optics applications transmitting and receiving over multiple fibers, the statement that these applications did not require all 12 fibers and that early 40GBASE-SR4 and 100GBASE-SR4 applications introduced in 2010 and 2015 respectively used only 8 fibers with 4 transmitting and 4 receiving at 10 Gb/s or 25 Gb/s, that initial deployments of 8-fiber applications often used 12-fiber MPO connectivity leaving the four center fibers inactive and essentially wasted, that this inefficiency prompted manufacturers to develop 8-fiber MPO connectivity and the industry designated the two solutions as Base-8 and Base-12, that the Base-8 MPO connector uses the same form factor as the Base-12 MPO but with the four center fibers removed, that data centers with existing Base-12 MPO infrastructure can upgrade to 8-fiber applications without wasting fibers by using MPO conversion patch cords or cassettes with a conversion cord or cassette breaking out two Base-12 MPOs of 24 fibers total to three Base-8 connectors also 24 fibers total, that while Base-12 MPO connectivity remains common for consolidating backbone cabling in duplex applications it is now rarely deployed for parallel optics because most current parallel optics applications use 8 fibers including 100 Gig with 4 fibers transmitting and 4 receiving at 25 Gb/s, 200 Gig with 4 transmitting and 4 receiving at 50 Gb/s and 400 Gig with 4 transmitting and 4 receiving at 100 Gb/s, the statement that the upcoming IEEE 802.3dj standard will also support 800 Gig over 8 single-mode fibers with 4 fibers transmitting and 4 receiving at 200 Gb/s, the definition that fiber optic polarity is critical for successful high-speed data transmission in MPO-based parallel optics links and that when polarity is not maintained the transmit signal at one end will not match the corresponding receiver at the other end resulting in a non-functional channel, the statement that there are three primary methods for polarity named Method A, Method B and Method C and that these polarity methods remain the same whether the parallel optics link uses Base-12 or Base-8 connectivity, the Method A description using Type A straight-through MPO trunk cables with a key-up connector on one end and a key-down connector on the other ensuring that Position 1 on one end of the link arrives in Position 1 on the other end, the statement that Type A adapters which mate two connectors key-up to key-down are used with a Type A MPO patch cord on one end and a Type B MPO patch cord on the other to ensure that the transmit corresponds with the correct receive and that the Type B cord is key-up to key-up which results in the fiber in Position 1 arriving at Position 12 and that per TIA standards only one Type B patch cord is allowed in a link, the Method B description using Type B reversed MPO trunk cables which feature key-up connectors on both ends causing the fiber at Position 1 to arrive at Position 12 at the other end, that Method B simplifies 12-fiber MPO polarity by using Type B trunk cables with Type B adapters which mate two connectors key-up to key-up and Type B patch cords at both ends of the link resulting in a key-up-to-key-up arrangement throughout the channel, that since the same type of patch cords is used uniformly throughout the channel any uncertainty about cord selection is eliminated, the Method C description using Type C cross-over MPO trunk cables that flip the pairs with the fiber in Position 1 arriving at Position 2 at the opposite end and the fiber in Position 2 arriving at Position 1 and so on, that while Type C MPO trunk cables work well for duplex applications Method C is not recommended for parallel optics, that supporting parallel optics with Method C requires Type A adapters key-up to key-down with a complex Type C MPO cross-over patch cord at one end to reverse the pair flip and a Type B patch cord at the other end and that Type C trunks and patch cables are not readily available, the statement that all single-mode MPO connectors use angled physical contact APC end faces which feature an 8-degree angle to improve reflectance, that it is now common to find APC multimode MPO connectors in the data center for high-speed 400 Gig and 800 Gig applications that are more sensitive to back reflections, that while Method B polarity is recommended because it uses the same patch cord types on both ends mating APC MPO connectors requires a key-up to key-down configuration for proper end face alignment, that this is why Type A adapters are almost always used in Method B polarity often referred to as Modified Method B, and that with Type A adapters the orientation of the Type B cable changes ensuring a key-up to key-down configuration to accommodate angled end faces, the guidance that polarity method should be determined during the design phase to ensure the correct components are purchased, that confusion surrounding polarity often leads to the discovery of incorrect cables or patch cords after installation, that since pre-terminated MPO assemblies and jumpers are typically made to order and often nonreturnable ordering the wrong polarity can lead to unexpected project delays and costs, that the Fluke Networks CertiFiber Max and MultiFiber Pro testers allow testing individual 8- and 12-fiber patch cords, permanent links and channels for correct polarity and automatically scan and test all 8 or 12 fibers for insertion loss results so that mistakenly ordered and installed Type B patch cords on both ends when trunk cables are Type A will be alerted, the statement that instead of having to reorder patch cords with the correct polarity or maintain a large inventory of different polarity types some UPC multimode MPO connectors allow changing polarity in the field which can save money and prevent delays by correcting mistakes on-site, the description of US Conec MTP Pro where the key position can be changed between key up and key down using a special tool with the connector inserted into the tool polarity-change port until it clicks then removed, the description of Panduit PanMPO where polarity is changed using an interchangeable housing that is removed, rotated 180 degrees and replaced to change the key position between key up and key down, that the PanMPO and MTP PRO also allow changing gender on both UPC and APC single-mode and multimode connectors by removing or adding pins so female-to-male mating can always be ensured at active equipment and adapters, that gender can also be changed on Senko MPO connectors as well as connectors offered by several connectivity manufacturers that license the US Conec and Senko connectors, and that polarity cannot be changed on APC connectors due to the angled end face — https://www.flukenetworks.com/blog/cabling-chronicles/getting-12-and-8-fiber-polarity-right
SENKO (Bernard Lee) — MPO Connector Polarity, TIA-568, covering the statement that unlike traditional 10GbE transmission which utilizes a 2-fiber configuration the 40GbE and 100GbE are implemented over multi fiber array MPO connectors, that it is critical that proper connector orientations are established, that the TIA 568 standard provides three methods for configuring systems to ensure proper connections are made, that these three methods differ in the cable orientation, connector orientation and the fiber assignment, the description of each MPO connector having a key on one side of the connector body and that the Key Up position refers to the orientation where the key is located at the top position of the connector, that when looking at the end face of the connector position 1 is on the far left while position 12 is on the far right and that for a 24 fiber MPO connector the same orientation applies with the top row being positions 1 to 12 and the bottom row being positions 13 to 24, that depending on the adopted connectivity orientation the MPO adapter needs to be suitable for its application which is either Key Up to Key Down or Key Up to Key Up, that MPO connectors are differentiated to a Male and Female connector, that a Male MPO connector has two alignment pins while a Female MPO connector has two alignment holes where the pins are to be inserted when a termination is performed, that an MPO connection can only be performed between a Male and Female connector to ensure proper alignment which is required to maintain a low loss connection, the Method A description as the Patch Cord Polarity Flip also known as the Transmit-Receive Flip having fiber 1 in position 1 in the MPO connector at both ends of the patch cord maintained throughout the network achieved by a 180 degree twist in the fiber orientation within the patch cord, that although the MPO connector orientation is maintained throughout the network two different types of duplex patch cords need to be installed which are a straight patch and a cross patch at the Transceiver and Receiver end, that this method is the simplest design to install and maintain as the orientation of the connector remains consistent, and that although two types of duplex patch cords are required this can be easily maintained by allocating one type of duplex patch cord to a fixed terminal to avoid a wrong installation, the Method B description as the Adapter Polarity Flip where the polarity at one end of the connector is flipped with fiber 1 located at position 12 while fiber 12 is located at position 1, that at the Transceiver and Receiver end only a straight duplex patch cord is required at both positions, that this method requires the installation of the patch cord to be exactly in accordance to the required orientation, that the connector orientation at the Transceiver and Receiver end are the same, that although the connector orientation at both ends of the patch cord is different the physical appearance of the connector is the same, and that the installer must have deep knowledge of the equipment and their positions to perform a correct connection, the Method C description as the Pair Polarity Flip being the most complicated method where at one of the patch cords two adjacent fibers are flipped in the MPO connector with fiber 1 in position 2 while fiber 2 in position 1 repeating throughout the whole connector, that at the Transceiver and Receiver end only a straight duplex patch cord is required at both positions, that this method is not suitable for a 100GbE transmission where Position 1 and Position 12 are not allocated, that since Positions 1 and 2 are paired as well as Positions 11 and 12 these four ports will not be usable, and that this reduces the usable positions to 8 which is insufficient for a 100GbE transmission — https://www.senko.com/mpo-connector-polarity-tia-568/
BWNFiber — MPO Breakout Cable: Types, Configurations, and How to Order the Right Assembly, covering the description of an MPO breakout cable as a pre-terminated assembly with one MPO connector on one end and several duplex connectors usually LC on the other connecting a parallel-optic port such as 40G SR4, 100G SR4, 400G DR4/SR8 or 800G SR8 directly to lower-speed duplex ports, the statement that the default specification for transceiver breakouts is Type B polarity, female MPO, and fiber count matched to the optic, that Type B polarity and a female MPO are the default for breakout cables plugging into transceivers because most QSFP, QSFP-DD and OSFP MPO ports are pinned male, that Base-8 suits 4-lane optics such as 40G and 100G SR4 and 400G DR4 while Base-16 suits 8-lane optics such as 400G and 800G SR8 and that Base-12 leaves four fibers dark on 4-lane links, that WDM interfaces cannot break out including 400G-FR4 and LR4 and 800G-FR4 and LR4 which carry all lanes on one duplex pair so there is nothing to fan out, that UPC is for multimode and APC for single-mode parallel optics such as 400G-DR4 and 800G-DR8 and that mixing UPC and APC damages end faces, the breakout cable description as a factory-terminated fiber assembly with one MPO connector on one end and several simplex or duplex connectors on the other where inside the cable the parallel fibers of the MPO MT ferrule are separated at a reinforced furcation point and routed into individual legs typically 2.0 mm tight-buffered cords with aramid strength members each ending in its own connector, the typical form factor table giving an MPO end of 8, 12, 16 or 24 fibers and a breakout end of LC duplex as most common plus SC duplex, CS and SN with breakout legs of 4, 6, 8, 10 or 12 duplex pairs and leg lengths of 0.5 to 2.0 m staggered or even with an overall length of 1 to 50 m, the transceiver mapping table giving 40G-SR4 on QSFP+ at 4 x 10G using 8 fibers on MPO-12 with 8 active and 4 dark via MPO-8/12 to 4x LC duplex, 100G-SR4 on QSFP28 at 4 x 25G using 8 fibers, 400G-DR4 on QSFP-DD at 4 x 100G using 8 fibers single-mode APC, 400G-SR8 on QSFP-DD at 8 x 50G PAM4 using 16 fibers multimode UPC via MPO-16 to 8x LC duplex, 800G-SR8 on OSFP or QSFP-DD at 8 x 100G PAM4 using 16 fibers multimode UPC, and 100G-SR10 legacy CFP or CPAK at 10 x 10G using 20 fibers on MPO-24 with 20 active and 4 dark, the table of MPO-to-LC breakout configurations including MPO-8 to 4x LC duplex for 40G SR4 to 4x10G and 100G SR4 to 4x25G and 400G DR4 to 4x100G, MPO-12 to 4x LC duplex for the same 4-lane optics on a Base-12 plant with 8 active fibers and 4 dark, MPO-12 to 6x LC duplex for full 12-fiber utilization with six duplex links consolidated from one 12F trunk port, MPO-16 to 8x LC duplex for 400G SR8 to 8x50G and 800G SR8 to 8x100G, MPO-24 to 10x LC duplex for legacy 100G-SR10 with 20 active fibers, and MPO-24 to 12x LC duplex for high-density duplex aggregation from a 24F backbone, the guidance to match the fiber mode to the optic rather than to preference with OM4 buying reach over OM3 so that 40G-SR4 runs 100 m on OM3 versus 150 m on OM4 and 100G-SR4 runs 70 m versus 100 m per IEEE 802.3, that OM5 only adds value for SWDM links and should not be paid for on standard SR4 or SR8, that single-mode OS2 legs of G.652.D fiber with APC polish belong to DR-class parallel optics such as 400G-DR4, that higher-speed SR8 optics shorten multimode reaches further so the transceiver datasheet should be checked for the exact limit before committing a length, that jacket color signals the mode at a glance with aqua for OM3 and OM4, Erika violet on some OM4 builds, lime green for OM5 and yellow for OS2 single-mode, the base comparison table giving Base-8 with 8 fibers as best for 4-lane optics including 40G and 100G SR4 and 400G DR4 with 100 percent fiber utilization as the default for new builds, Base-12 with 12 fibers best for existing Base-12 structured cabling with the warning that 4 fibers go dark on 4-lane optics, Base-16 with 16 fibers best for 8-lane optics including 400G and 800G SR8 and AI GPU fabrics with the warning that it is not interchangeable with Base-12 keying conventions and should never be mated by force, and Base-24 with 24 fibers for backbone aggregation and legacy SR10 with the most complex polarity management, the statement that Base-8 has become the default for new data centers because it maps 1:1 onto 4-lane transceivers and that Base-16 is the matching choice for 400G and 800G SR8 cluster builds, that removing the cassette removes one mated connector pair from the channel typically worth about 0.75 to 1.0 dB of insertion loss budget which matters on margin-tight multimode links, and the guidance that on a quote the connector type and fiber count for both ends are stated line by line and should be checked against the port map before approving — https://www.bwnfiber.com/mpo-breakout-cable/