The Fenix ALG-18 Barrel Mount, is a great solution for mounting a flashlight to a rifle that does not have rail attachment points. With no extra tools necessary, attach the mount to any gun barrel that is 18-23mm in diameter for a secure fit. For use with most of Fenix flashlights that have a body diameter of 23.5-28mm. If the Fenix ALG-18 Barrel Mount is used on a barrel with high volume rounds, the heat of the barrel will require you to remove the rubber cushions before using to avoid the rubber from melting. Features : Tool-free Assembly and Disassembly Made of A6061-T6 Aluminum "Fits Weapon Barrels with Diameters of 0.7"-0.9""