The Umarex (VFC) 30rds Magazine for Umarex UMP9 GBB SMG is a polymer encased metal construction magazine for the Umarex UMP9 GBB SMG series and holds 30 rounds of BBs. Green gas only. If you own a Umarex UMP45 gas blowback rifle, then this UMP9 gas magazine will also work with your gun. The gas magazines of the UMP45 and UMP9 are interchangeable.
I ordered 2 of these for my umarex UMP45 GBB, they're supposed to fit but for me they didn't so I guess only get these if you have a UMP9.
The mags feel like they are very good quality with great materials. The mags are very very heavy though, so sticking 5 of these in your vest can get very heavy very quick.