Mk1 Bren magazine

[Brit plumber]

Unfortunately I believe there are some fake Mk1 mags out there. By fake, I mean mags that have been converted back to mk1. So far they all appear to use ZB39 mag covers. So check markings carefully if it's costing an arm and a leg. If it's in a box of hundreds and it's only a fiver, chances are it's genuine!