CycleBeam(TM) 700 Lumen Long Run Time Bike Light | The Most Rugged Bike Light You Can Find on Amazon Extremely Bright: CREE XM-L2 LED Bulb Large Battery Capacity: Light weight 33 WH Li-ion battery pack is included. Long Run Time: Light for up to 15 hours depending on which brightness level you choose. (5 hr at High, 15 Hr at Low). Weather Resistant: Tough, water-resistance, aircraft-grade aluminum housing is designed for efficient heat dissipation (longer battery life). Strong Material: The whole light including the mount is made with aluminium.