Osprey MK IV and MK IVA: which is which, and what fits
Osprey is the British Army's modular body armour, and it has been through four marks since 2006. Secondhand kit turns up labelled MK IV, MK IVA, Mk4A and MK4 interchangeably, which leaves one question worth answering: if your vest is one mark and the pouch is the other, does it still fit?
The short answer
Yes. A MK IV pouch fits a MK IVA vest and the other way round, because the mark describes how the VEST carries its armour plates, not how a pouch attaches to it.
Pouches attach by PALS - the same grid of 25 millimetre webbing loops used by American MOLLE kit and by almost everything else in this shop. The rest of this page is why that is true, and the one part that does differ.
The marks, briefly
MK 1, 2006. The first version, brought in after Iraq to replace Enhanced Combat Body Armour, with large ballistic plates front and back.
MK 2, 2007. Revised pouches, drop sling attachments for a rifle, better construction, and the introduction of a waist cummerbund.
MK 3. A stronger right shoulder assembly and a non-slip shoulder pad. The MK 3A added studs on the plate pockets to hold the hard plates more securely.
MK 4, April 2010. The hard plates moved inside the vest rather than sitting in external pockets, velcro coverage improved, and the system came with 23 pouches.
MK 4A. The outer cummerbund was removed and replaced with dedicated pouches for the side armour plates.
MK IV against MK IVA, which is the one that matters
Both carry side armour plates. They differ in where those plates live.
The MK IV carries them in the cummerbund - the wide belt that wraps the waist. The MK IVA does away with the cummerbund altogether and carries them in separate side plate pouches instead.
That is not a cosmetic change. The cummerbund occupied the same real estate as the OPS panel, so on a MK IV you could have one or the other. Dropping it is what lets a MK IVA wear the OPS panel and the side plates at the same time, and it takes weight off the waist while giving you some choice about where the plates sit.
If you want the evidence rather than the explanation: the two MK IVA items in this shop are an OPS panel and a side plate carrier pouch. Those are precisely the parts the MK 4A redesign created, and they have no MK IV equivalent because on a MK IV the cummerbund did that job.
The two ways an Osprey pouch attaches
Most Osprey pouches use what the Americans call the Natick snap, and it is the same method as any MOLLE pouch: the webbing strap on the back weaves down through the rows on the vest and back through the pouch's own ladder, alternating, then a press stud finishes it.
Some use a T-bar clip instead - a fixed strap with a 25 millimetre ITW Nexus buckle and a moulded T at the end, which slides under the vest's webbing and sits across it. Quicker to fit and quicker to lose, which is why loose T-bars and ITW straps are sold as spares at all.
Both go onto ordinary PALS. If a second-hand pouch arrives without its clips, a 25 millimetre ITW Nexus attachment strap replaces them; it is the same part, not a workaround.
Telling genuine issue from a copy
Issued Osprey carries a stores label with a NATO stock number. Personal armour sits in NSN group 8470, and a British contract reads 8470-99 - the 99 is the United Kingdom.
Camouflage dates it too. MK 3 was mostly Desert DPM. MK 4 was issued in Desert DPM, in plain tan and in MTP, so an Osprey pouch in MTP is MK 4 era rather than anything earlier.
What this guide does not tell you
Plate sizes, protection levels and what will actually stop. There is no public specification for Osprey, and the honest position is that the chronology above comes from published reference material rather than from a document the Ministry of Defence has released.
Nothing in this shop is armour. The Osprey items here are covers, pouches and panels - the fabric that carries plates, not plates.
Questions
- Will a MK IV pouch fit a MK IVA vest?
- Yes, and the other way round. The mark describes how the vest carries its side armour plates, not how a pouch attaches. Osprey pouches attach by PALS, which is standardised, so they also fit American MOLLE platforms and most commercial plate carriers.
- What is the difference between Osprey MK IV and MK IVA?
- The MK IV carries its side armour plates in the cummerbund. The MK IVA has no cummerbund and carries them in dedicated side plate pouches instead, which is what allows the OPS panel and the side plates to be worn together.
- Why does my Osprey pouch have a T-bar instead of a strap?
- Osprey uses two attachment styles. Most pouches use the usual woven strap and press stud; some use a fixed strap with a 25 millimetre ITW Nexus buckle and a moulded T-bar that slides under the vest webbing. Both fit standard PALS.
- My Osprey pouch is missing its clips. Is it useless?
- No. A 25 millimetre ITW Nexus MOLLE attachment strap is the same part and replaces them. Missing clips are the commonest thing wrong with second-hand Osprey and the cheapest to put right.
- Is MTP Osprey the newest?
- MTP Osprey is MK 4 era. MK 3 was issued mostly in Desert DPM; MK 4 came in Desert DPM, plain tan and MTP.
- Is any of this body armour?
- No. Everything here is the cover, the pouch or the panel - the fabric that carries a plate. No hard armour is sold on this site.
Sources
In the shop
The Osprey and the kit that goes with it:
Written by the person who sorts the stock, not by a copywriter. Corrections are welcome at [email protected].