Meant to be installed from the left to the right; The dovetail has a progressive taper to allow for easier install; Mounting hardware included; 2 Button Head Cap Screws - Provided for Vortex Viper and Venom Sights; 2 Flat Head Cap Screws - Provided for Burris FastFire and Docter Sights; The screws require a 5/64'' allen wrench for installation