Awesome! I have these for my entirely custom gun with a G4 body and G&G hop up. They help about 140 at first but they've settled to about 1 speed loader fill, so 100 rounds. They can keep up with my 35+ rounds per second perfectly, never had to lube them! Magpuls fit nicely on them with minimal movement, I've painted these mags to match the paint job on my gun, no problems. Buy them!
Awesome capacity (I just use these, no hi-caps).
Hold 100 rounds.
Keep up with 35+ RPS.
Tight in my magwell, but still easily removed (they can't fall out).
Kind of a satin finish, but I painted mine!
There's a little trap door that screws onto the bottom, don't mess with it! It holds the bottom of the spring and I almost broke a mag trying to get it back in.
RARELY they get annoying and the spring will bind up, but it's because I haven't ever lubed them I think.
Rating: [5 of 5 Stars!]