Thanks Mckay, that's what I ended up figuring out too.
TBREW - yep I've been using the 33 round version for a long time, the black one in the pic is an old one. It's the 24 round, and the brown colored 33 and 17 round that are new. The brown colored mags are to match the new gen 5 guns, and it looks like the bright orange followers came out about the same time. They all work well, just minor improvements over the years.
