Revtronic BT40S 1600 Lumens Bike Light - Cree LED Bike Lights - Mountain Bike Headlight (Light Head Only) Four Cree XP-G (R5) LEDs, max output 1600 lumens(Warm White LEDs) 4 level adjustable brightness Powered by 7.4V 4400mAh rechargable li-on battery pack Not Included Digitally regulated output maintains constant brightness Fits 20mm-35mm handlebars or mounts on helmet via o-ring straps