Burris 410348 AR-F3 Mount Matte BlackThe Burris AR F3 is the simplest, most effective way to mount any FastFire sight on an AR flattop. It allows the FastFire to be mounted at the optimum height, so the red dot can co witness with flip up sights. The metal wings protect the lens from impact and unintentional abuse. The lower compartment stores spare battery, open end wrench and a Torx wrench.