Monstrum Gun Plug Screw Set for Rifle and Shotgun Receivers Compatible Across Most Major Makes and Models. Most receivers have factory mounting holes for installation of an optics base - gun plug screws are designed to plug these holes cleanly when the rail is removed. Includes both #6-48 and #8-40 gun plug screws for compatibility across most major makes and models. Check with your manufacturer to confirm the drill hole pattern of your firearm. Gun plug screws are 1/8 inch in length - allowing for installation flush with the top of the receiver without penetrating too deeply. Gun plug screws are not suitable for fastening an optics base. Includes 10 plug screws of each size plus hex wrench. Screws crafted from hardened steel to prevent stripping. Includes blue loc-tite for secure fastening. All Monstrum products are backed by a lifetime guarantee Specifications for Monstrum Gun Plug Screw Set for Rifle and Shotgun Receivers: Manufacturer: Monstrum Length: 0.25 - 20 mm Head Type: Hex Type: Gun Plug Screws Package Contents: Monstrum Gun Plug Screw Set for Rifle and Shotgun Receivers Monstrum T25: Gun Plug Screw Set for Rifle and Shotgun Receivers Compatible Across Most Major Makes and Models