I installed one of these on each magazine and they add 0.5 of an inch to your grip. They are easily installed but depending on what model you have it may take a one time sanding on the lip on the bottom. I used a small file until they fit flush. Filing the lip will not harm the extension. You are just catering the fit until you feel a good snap of the latch into the mag well. Your mag will drop free when the fit is right for you. I really like them, you will appreciate that 1/2 inch of control. Well worth the money.