The Nitecore GM02 Pro is constructed from aero grade aluminum alloy with HA III military grade hard-anodized finish for rugged durability. A large stainless steel thumb nut allows easy adjustment and ensures stable mounting on a Picatinny (MIL-STD-1913) rail. Fits flashlights witha body diameter of 1 inch (25.8mm - 26.5mm). Compatible Nitecore Models: SRT6i, SRT7i, MH12 Pro, and MH25 Pro.