USB RECHARGEABLE - A built in micro usb port allows for fast charging so the HC35 is always ready to go. MULTIPURPOSE DESIGN - A quick detach bracket allows the HC35 to be used as a handheld flashlight or worklight with a magnetic tailcap and pocket clip. CONTENTS: HC35 Headlamp;NL2140HP 4000mAh 21700 Rechargeable Battery;Spare O-ring;Clip;Headband;Bracket;18650/2xCR123 Battery Adapter;USB Charging Cable;Lanyard HIGH PERFORMANCE HEADLAMP - NITECORE HC35 is capable of 2700 lumens at over 146 yards of throw. Freely rotate the light on the headband mount for directional illumination. CONVENIENT BATTERY OPTIONS - Comes with an included high performance, 21700 li-ion battery, but will accept 18650s (>8A) and even 2x CR123 or 2x RCR123 batteries in a pinch.