FD65 is fitted with Cree XHP35 HI LED’s, plus high efficient TIR optical lens, it emits a max output of 3800 lumens and beam distance of 410 meters. Rotating the focusing ring moves the head forward and backward, thus regulating the focus between spot- and floodlight. Click the H switch to activate High output and increase brightness, while L switch to activate Low output and decrease brightness. It is normally powered by four 18650 rechargeable Li-ion batteries ( Batteries Not Included ) , 2 batteries are also available for emergency use. In addition, the IP68 rated protection, momentary on strobe and SOS function make FD65 perfect for caving, outdoor photography, searching and rescuing.