SureFire M Series Scout Light, LED WeaponLights with TIR Lens and Tumbscrew Mount High-performance, recoil-proof LED generates 500 lumens of blinding white light and continues producing tactical-level light for 1.5 hours Total Internal Reflection (TIR) lens creates intense, versatile beam with enough reach for longer-range applications and significant surround light for peripheral vision Tailcap click switchpartially press for momentary on, click for constant-on activation; patented lockout feature prevents accidental activation Construction: Mil-Spec hard-anodized aerospace aluminum, optically coated tempered window, O-ring and gasket seals Thumbscrew clamp securely attaches to any MIL-STD-1913 (Picatinny) rail