Mounts to the rib without tape screws or magnets - Special nylon liner protects rib and locks metal sight in place - Extremely low profileFull windage adjustment - CNC-machined - These CNC machined steel sights incorporate light gathering fiber optics for a brilliant sight picture in almost any conditions. A universal Slide-Lok mounting system allows use on any shotgun with a ventilated rib while a nylon liner protects the rib from damage to its finish. Sights are windage and elevation adjustable. Hardware included. Front diameter is .060; rear diameter is .035.