well i got this for my ks90 box mag and it worked when i tested if out in the backyard. then i went to play a game with my friends but finally when we got to the field the mag stopped feeding. come to find out the pin holding one of the gears fell out and the when i finally got the pin it it didn't feed at all come to find out the spring inside of the mag was also broken and after and hour of working on it and getting attacked by the spring it works fine now. i would suggest getting it i think i just got a lemon cus it didn't have any glue to hold the pin in.
has winding key(makes going thought 1500 rounds easy to do)
the spring attacked me
took forever for me to fix
Rating: [4 of 5 Stars!]