3" overall. Water resistant. Impact resistant. Lanyard. Three modes: Constant On (100%, 5.5h runtime), Constant On (25%, 27h runtime), Flash (1 Hz). 360 degree viewing angle. 850nm Infrared Ray LED. Can be attached to OPS-CORE ARC helmets, 1" webbing, and any Velcro loop surfaces. Body with scrub treatment to reduce surface reflections. Includes GTK mount and O-ring. Requires (1) AAA battery (included). Boxed with hanging tab.