MPO Cable Selector Guide: Polarity (Type A, B, C), Male vs Female, and 8/12/16/24-Fibre Explained
Last reviewed: 22/10/2026
One wrong detail on an MPO order, such as the wrong gender, polarity or fibre count, means a link that won't come up, a damaged end face or a re-order that costs you weeks. This guide takes you from "which MPO cable do I need?" to a spec you can send to any supplier. It covers the connector itself, MPO vs MTP®, fibre count, pinned vs unpinned, Type A/B/C polarity, polish and fibre type, a selector table for common optics and a 12-point order checklist.
Televers supplies Televers-branded MPO patch cords and MPO to LC breakout cables from New Delhi, and our team will check your BOM before you order.
MPO in 60 seconds: ferrule, key and pins
Direct answer: An MPO connector holds 8 to 24 fibres in one rectangular MT ferrule. A raised key on one side sets orientation (key up or key down), a white dot marks Position 1, and the male (pinned) connector has two guide pins that align it with the female (unpinned) connector inside an adapter.
MPO stands for multi-fibre push-on. The interface is defined in IEC 61754-7 (part 7-1 for one row of 12, part 7-2 for two rows, part 7-3 for the 16-fibre version) and in TIA-604-5 (FOCIS-5). A standard 12-fibre MPO has one row of 12 fibres, numbered Position 1 to Position 12 when you look at the end face with the key up.
Two MPO connectors work together only if the fibre count and key layout match, one side is pinned and the other unpinned, and the polish is the same.
Short version: MPO quick introduction
MPO vs MTP®: connector type vs brand
Direct answer: MPO is the connector type. MTP® is US Conec's trademarked MPO-style connector, built to intermate with standards-compliant MPO connectors. Think of MPO as the product category and MTP® as one branded product in it. Polarity, gender and fibre count work the same way on both.
The two terms are often used loosely, as if they were one thing. MPO is defined by IEC and TIA standards and is made by many companies. MTP® is a registered trademark of US Conec Ltd, used for its own connector family. US Conec states that MTP® connectors are designed to intermate with standards-compliant MPO connectors.
What this means for your order:
Specify the fibre count, gender, polarity, polish and loss grade. These matter far more than the label on the connector body.
Only call a cable "MTP" if it genuinely uses US Conec MTP® connectors.
Televers supplies MPO assemblies. We do not sell MTP® connectors.
Fibre count: 8, 12, 16 or 24
Direct answer: Match the fibre count to the optics. 40G and 100G SR4 and 400G DR4 use 8 fibres, carried in a 12-fibre MPO. Most 400G SR8 and 800G SR8 or DR8 optics use a 16-fibre MPO, which has an offset key and does not mate with MPO-12. 24-fibre suits high-density trunks.
Why a 12-fibre MPO carries only 8 fibres for SR4
MPO-16 (IEC 61754-7-3) has one row of 16 fibres and an offset key, so it physically cannot plug into an MPO-12 adapter. Many 400G SR8 and 800G SR8/DR8 transceivers use it. Always confirm the connector on the transceiver datasheet.
16-fibre MPO for 400G and 800G
Parallel optics such as 40GBASE-SR4 and 100GBASE-SR4 send on four fibres and receive on four. In a 12-fibre MPO, Positions 1–4 transmit, Positions 9–12 receive and Positions 5–8 are unused. That is why "Base-8" cabling exists: it uses all fibres in the trunk. More on this: Base-8 vs Base-12
Male vs female (pinned vs unpinned)
Direct answer: Pinned always mates with unpinned, through an adapter. Transceivers are pinned, so the cords that plug into them must be female (unpinned). Never mate pin to pin or hole to hole. Cassettes and panels vary by vendor, so check the cassette gender before ordering a trunk.
The rule is simple, and getting it wrong is the most common MPO ordering mistake:
Male (pinned): two steel guide pins stick out of the ferrule.
Female (unpinned): two holes receive the pins.
Transceivers (QSFP, OSFP and similar): the port is pinned, so the patch cord end is female.
Cassettes and panels: often pinned inside, with an unpinned trunk, but this is not universal. Check the vendor's datasheet.
If you mate two pinned connectors, the pins hit the opposite ferrule and can scratch or chip the end faces and bend the pins. If you mate two unpinned connectors, nothing aligns the fibres, so loss is high or the link fails.
Polarity explained: Type A, Type B, Type C
Direct answer: Polarity decides which fibre position arrives where. Type A is straight-through (Position 1 to 1, key up to key down). Type B is reversed (1 to 12, key up to key up). Type C flips adjacent pairs (1 to 2). Type B is the usual choice for direct links between parallel optics.
Type A: straight-through
"Type" describes one cable. "Method" (A, B or C in ANSI/TIA-568.3-E) describes the whole channel: trunk, cassettes or adapters, and patch cords. Pick the method first, then order cables that fit it. Short explainer: MPO polarity
Type B: reversed (the "crossover")
Position 1 arrives at Position 1, with key up at one end and key down at the other. In a Type A channel (Method A), the transmit-receive flip has to happen elsewhere, so you need an A-to-B duplex cord at one end and an A-to-A cord at the other. Cords are easy to mix up.
Type C: pair-flipped
Position 1 arrives at Position 12, 2 at 11 and so on, with key up at both ends. This reversal sends every transmit fibre to a receive position, so a Type B cord between two SR4 transceivers works without any other flip. In a Type B channel (Method B), the same cord type works at both ends.
Cable types vs polarity methods
Position 1 arrives at Position 2, 2 at 1, 3 at 4 and so on, with key up to key down. It suits some duplex designs but not 8-fibre parallel optics.
Polish and fibre type: UPC vs APC, OM3/OM4 vs OS2
Direct answer: Single-mode MPO (OS2) is normally APC, an 8° angled polish. Multimode MPO (OM3, OM4) is usually UPC, but some newer multimode optics specify APC, so check the transceiver datasheet. Never mate APC with UPC. Use OM3 or OM4 for short-reach SR optics and OS2 for DR and longer reaches.
OM3 and OM4: multimode, aqua jacket by common convention (OM4 is sometimes violet). OM4 supports longer reach than OM3 at the same speed. Check the optic's reach table.
OS2: single-mode, yellow jacket by common convention, used with DR4, DR8 and PSM4 optics.
Colour is a hint, not a spec. Green connector bodies usually mean APC, but always confirm on the label or datasheet.
Related: UPC vs APC and single-mode vs multimode
The MPO selector table
Direct answer: Start from the transceiver at each end. Its datasheet fixes the fibre count, polish and fibre type. The rows below show the usual cable for common links. Televers stocks a few 12-fibre OM3/OM4 Type B female-female cords; other builds are made to order or available on request.
Find your application, then order what the row says. Confirm against your transceiver datasheet.
See our MPO patch cords, including 12-fibre OM3 MPO, Type B and 12-fibre OM4 MPO, Type B, 5 m.
Not sure? Send us the transceiver part numbers at both ends and we'll tell you the exact cable.
How to specify an MPO order: the 12-point checklist
Direct answer: A complete MPO order states the optics at both ends, fibre count, fibre type, connectors, gender at each end, polarity, polish, loss grade, cable and jacket, length, test-report needs, and labelling and delivery. Copy the checklist below into your RFQ or purchase order so nothing is left for the supplier to guess.
Copy this into your RFQ:
Transceiver part numbers at both ends (or panel/cassette model)
Fibre count: 8 / 12 / 16 / 24
Fibre type: OS2 / OM3 / OM4 / OM5
Connector at end A and end B: MPO, or LC/SC legs for breakouts
Gender at each end: pinned (male) / unpinned (female)
Polarity: Type A / B / C
Polish at each end: UPC / APC
Insertion-loss grade: standard or low-loss, with the maximum dB per mated pair
Cable: round or ribbon, outer diameter, jacket (LSZH / OFNR / OFNP), armoured or not
Length and tolerance; for breakouts, leg length and stagger
Test report needed: IL/RL per fibre, end-face inspection, polarity check
Labels, packaging, quantity and delivery location
What a test report should show
A good MPO test report lists insertion loss (IL) and return loss (RL) for every fibre, end-face inspection results to IEC 61300-3-35, end-face geometry (3D interferometry), and a polarity check. As typical industry figures, a standard MPO mated pair is often specified at up to 0.75 dB IL and a low-loss grade at around 0.35 dB. Ask your supplier for their actual specification.
At Televers, test reports are available for custom orders, or on request. Stock cords ship without an individual test report.
Testing and fixing polarity on site
Direct answer: Use an MPO polarity tester or an MPO-capable certifier to confirm the fibre mapping and loss before handover. If polarity is wrong, swap the patch cord or cassette for the correct type, rather than re-terminating. Inspect and clean every end face before mating, then inspect again.
A polarity tester lights each position and shows where it arrives at the far end. A certifier also measures loss per fibre.
Dirt is the commonest cause of high loss: inspect, clean, then inspect again.
Frequently asked questions
Is a Type B MPO cable a crossover?
Yes, in effect. A Type B cable reverses the fibre order end to end, so Position 1 arrives at Position 12, using key-up to key-up connectors. That reversal sends each transmit fibre to a receive position, which is why direct transceiver-to-transceiver MPO links use Type B.
Can a 16-fibre MPO plug into a 12-fibre MPO adapter?
No. MPO-16 has an offset key and a different fibre layout, so it does not fit MPO-12 adapters or mate with MPO-12 connectors. If your optics are 400G SR8 or 800G SR8/DR8, check the datasheet; they usually need MPO-16 cords end to end.
Do I need APC or UPC MPO connectors?
Follow the transceiver datasheet. Single-mode MPO for DR4, DR8 and PSM4 optics is normally APC. Multimode SR4 optics are usually UPC, but some newer multimode optics need APC. Both ends of a mated pair must have the same polish.
Which MPO cable do I need for 100G SR4?
A 12-fibre MPO patch cord, Type B polarity, female on both ends, in OM3 or OM4 fibre, typically UPC. OM4 gives longer reach than OM3. Televers keeps a few 12-fibre OM3/OM4 Type B cords in stock and makes custom lengths to order.
Does Televers sell MTP® cables?
No. Televers supplies MPO patch cords and MPO to LC breakout cables, not US Conec MTP® products. For most links the specification that matters is fibre count, gender, polarity, polish and loss grade, which we match to your optics.
Can Televers check my MPO bill of materials before I order?
Yes. Send us your BOM or the transceiver part numbers by WhatsApp or through the contact form, and our team will check gender, polarity, fibre count and polish against your optics before you place the order.
Get your MPO BOM checked before you order
Direct answer: Televers is an RF and fibre connectivity supplier based in Janakpuri, New Delhi, shipping across India. We supply Televers-branded MPO patch cords and MPO to LC breakout cables, built to Televers specifications by a contract-manufacturing partner, and we check customers' MPO BOMs before they order.
Who we are: Televers, an RF and fibre connectivity supplier and authorized representative in India for global brands: RFS, Spinner, NetPoint.
Where we are: Janakpuri, New Delhi, India. We ship across India.
What we supply in MPO: Televers-branded MPO cables, built to Televers specifications by our contract-manufacturing partner. Mainly 12-fibre MPO with Type B polarity, in OM3 and OM4 multimode; OS2 single-mode on request. MPO to LC breakout cables are also available.
Stock and lead time: a few 12-fibre OM3/OM4 pieces in stock. Bulk orders and custom lengths dispatch in 3 to 4 weeks.
Test reports: available for custom orders, or on request.
Not supplied: US Conec MTP® connectors or cables.
How to order: send your BOM through contact or WhatsApp, buy on MPO patch cords, or order on Amazon: https://www.amazon.in/dp/B0HKZG487R , https://www.amazon.in/dp/B0HF464BG8
About Televers
Direct answer: Send us your BOM, or just the transceiver part numbers at both ends, and Televers will check gender, polarity, fibre count and polish before you place the order. It's the quickest way to avoid a dead link or a re-order. Reach us on WhatsApp or through the contact form.
We'll confirm the right MPO patch cords or breakout cables, tell you what's in stock and give you a dispatch time for custom builds.
