Fortified Bicycle Alliance 50 Lumen LED Defender Bike Headlight Battery life: 50 hours steady beam, 100 hours flashing - 3-AA batteries included Theft-proof lightweight aluminum bike headlight locks on to handle bars with custom security screw Weather-proof bike light is built to withstand all riding conditions Six LED lamps provide 50 lumens of brightness with 30 degree primary beam angle - 80 degree secondary beam angle Fits all handlebar sizes (22mm - 32mm)