It's just a leg that attaches to the rear of the rail and supports it against the slide should it be pressed down at the rear for some reason. I didn't bother to install it. The whole thing still overpowers the pistol and looks ugly but it works fine. You have to remove this contraption to remove the slide and I don't like that. That's why I'm working on a small, lightweight red-dot that will mount directly to the slide.
1911M
