It looks like a copy of the Hero Arms C-mag, I have the HA mag, fed well with excell .02, but the plastic seemed brittle and the cut down G36 mag bolted to the top collapsed while I was loading it, the spring that pushes the ammo out of the drum into the feed mech is really strong and puts a lot of load on the mag when you have to hold it back while loading, I think I must have been twisting it too much or something.