Things I liked: Everything (Co2 and BB's) are contained in the mag. The size and weight of the mag adds to realism for training purposes.
Things I would have changed: The valve/seal that accepts the Co2 cartridge is threaded counter to the natural clockwise rotation of the C02 cartridge as its being screwed in. The result is that the valve/seal unscrews as the C02 is tightened. Should have included a proper tool for keeping the valve/seals tight, as a flat-head screwdriver is a bit awkward.
What others should know: The valves/seals need to be tightened every so often or they will eventually leak.
Things I liked: Very well made. I put this on my Umarex EBOS. I was worried about it being tall enough to get over the BB hopper at the end of the gun. It works like a charm. No riser or extension required. I'm very happy with the result.
Things I would have changed: Nothing
What others should know: Works right out of the box with Umarex EBOS.