The TRUGLO Magnum Gobble-Dot Xtreme Standard/Magnetic Mount Sights offer increased visibility and accuracy under the most extreme conditions. The magnetic mount design offers lasting performance, without the need for any adhesive or custom gunsmithing. FEATURES: - Each model easily snaps over rib without need for screws - Front diameter is .060""; rear diameter is .035"" - Endorsed by the National Wild Turkey Federation.