i was told by a long-time UC II owner that these mags worked SO much better for him than the fac mags from Kimber. so i bought an 8 round WC mag at a gun show last weekend, and it is so much better quality. i haven't shot with it yet. it sticks down past the butt a little, but i got it for backup. i 'm getting a 7 rnd one for regular use.i surely think they are the only to have with our K ultra carrys. don't ya love how these little guns operate and feel and shoot?!