Basic Fast 502 model integral thumbscrew clamp can attaches to any keymod series handguard, It is equipped with a remote switch and a pressure switch. With a simple but reliable one brightness mode only, can reach a maximum of 800 lumens  bright light, quickly illuminate the front area.single-output Tactical-Light，Use two CR123 batteries or one 18650 battery,Higher reliability and durability

OPSMEN FAST 502K Weapon Light for Keymod System (800 Lumen)
A premium CREE XM-L2 (U3) LED offers maximum output of 800 lumens
Precision Optics Technology for extreme reflector performance
Boasts a peak beam intensity of 10000cd and throw distance of up to 200 meters
Made by aerospace grade 6061-T6 aluminum alloy
Constructed from aero grade aluminum alloy with HAIII military grade hard-anodized finish
Toughened ultra-clear mineral glass with anti-scratch coating
Two Tail cap switch options. designed for tactical application
Waterproof in accordance with IPX-8 (two meters submersible)
Impact resistant to 1.5 meters

Length: 137.2mm (5.4”)
Head Diameter: 32mm (1.26”)
Tail Diameter: 25.4mm (1”)