5 1/4" overall. Black high impact ABS construction. White LED. 110 lumens. Runtime: up to 8h. Visibility: up to 304ft. Water resistant: up to 10ft. Features Thermal Recovery System that transfers heat from the LED to warm batteries for better cold weather performance. Waterproof. O-ringed sealed. Compound Path Optics (CPO) permits high efficiency and compact size. Push button tail cap switch. Uses three AA batteries (included). Can be mounted to any helmet or hard hat using a UK helmet clip. Hang packaged. Made in USA.