The Fenix ALG-15 Tactical Rail Mount features tool-free rail attachment. The simple rotary knob allows you to hand tighten the mount onto your Picatinny rail, with the option of using any simple tool to tighten it further with the tool notches. The body is made from durable hard-anodized aluminum alloy and is lightweight but strong enough to resist recoil. Compatible with most flashlights with a body diameter between 22.5mm-26mm (0.89-1.02 inches) and a head diameter of less than 40mm (1.6 inches)