This is a must have item for Californians due to 10 round magazine limit law effective Jan 1, 2017. I used these limiters in my STI 126 mm mag bodies combined with a Dawson baseplate. The fit was good but when checked, the round count was 9 not 10 as expected. Be sure to check yours on assembly! The fix was easy. I had to shorten the limiter by about 1/4 " to get the round count right. This was done first and the the baseplate riveted for permanence. You would not need the riveting if you live in an unrestricted state. Function is fine and complies with the law.