Its a magazine, and there's not much to say about it other than it works. Compatible with KWA USP Compact & Compact Tactical. (Description doesn't say it.) If you have either of those two guns, this is your only option. No other brand makes it.
I recommend filling gas in two increments of 5 seconds. That will get you through around 40 rounds.
-Big gas resovoire
-Has been dropped about 4 feet onto concrete, still works
-none, besides the fact that you WILL NOT finish a mag if you put less than 7 seconds of gas in.
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