I wish that I had bought this sooner. My Rock Island Big Rock mag release was defective from the factory, I replaced it with a W. Combat mag release that took substantial custom fitting on the diameter to make it work. After around 3,000 rounds that other aftermarket mag release wore out. This one dropped right in. I also got the extended length and oversize button. The only problem was that if I pushed the button sloppily the pear shaped base would hang up on the outside of the frame. Ramming the next magazine into the well always re-seated to assembly properly but I still spent a few minutes with a file so that I could be as sloppy as I wanted to be without any potential issue. This product is another great example of the Dawson Precision attention to detail: starting with what is required and the continuing with what more is needed and not even calling that finished until they have added what is wanted. I have full confidence that this mag release will last MUCH longer than 3,000 rounds. The only problem with this product is that I am going to feel clumsy when I use my standard 1911. For fitting reference purposes, Big Rock = Rock Island 1911 A2 10mm Pro Match Tac Ultra 6" HC P/N 520009.