Bought this with the grey version from Eliteforce, and overall, this is a great mag! It feeds well with all brands of bb's, and it is very durable and works well with my King Arms M&P15 and my Real Sword Type 97b.
The only issues is that the paint will scratch off eventually with the magwell contact and that it is slightly wider than the other brands, such as Echo 1 and Tokyo Marui, but this wideness allows the mag to fit snuggly in the magwell with no rattle or movement.
+/- Wider (As a pro, this equals no movement so no worries with it dropping out)
Paint chips off
+/- Wider (As a con, you actually have to hit the mag to lock it in, but after that, its fine.)