"This is a must if you own a gas m1911 because it saves tons of time. The mag holds around 27-28 bbs, and the amount of ammo that you can have with multiple mags is crazy. One thing that you need to be aware of that is after filling up the mag each time with gas, check and make sure you see that the small rubber ring around the nozzle has not fallen off. Losing that rubber ring can cause your mag to leak gas. Overall this is a good mag and I highly recommend it."