Can't really say for sure where the AIM "Euro" mags came from as there are no markings that I could immediately see but they all look like the one in your picture with the solid catch. They may have been used but look more or less like they are in new condition. They smell like they have some light cosmoline on them, could be just some other type of protecting oil though. The follower looks kinda similar to Yugo mags with the bolt hold back but I haven't checked yet to see if it works that way.I've heard AIM's latest mag sale
includes some Chinese "flat-back" mags......
I checked to see if any of them had the stamped catch but none of them did.