One of the lightest brightest most comfortable head-lamps available today. Features High anf Low lighting modes and a runtime up to 24 hours. Powered by two 1.5V AAA cells (included)..5 watt high-flux 100000 hour life LED. Up to 14.5 lumens typical and up to 850 peak beam candlepower (high mode); 6 lumens typical (low mode). Solid State Power Regulator provides maximum light output throughout battery life. Up to 6 hrs runtime on high mode; up to 24 hrs on low mode. Impact-resistant drop-tested housing. O-Ring sealed construction. Waterproof to 1 meter for 1 hr. Facecap diameter: 1.3 in. Max. headlight with: 2.25 in. Max. headlight depth: 1.6 in. including head strap and mounting strap. 2.75oz with battery and head strap. Includes rubber/elastic combo head strap.