Serfas Thunderbolt USB Headlight The industry's most technologically advanced safety lights All lights are robs compliant and all testing is done in house More efficient leds & high quality lenses to increase brightness & Clarity Produces 90 lumens of pure light USB rechargeable light, that fully charges in 3.5 hours Features 15-micro (double strength) LED strip Features a water resistant silicone body and unique mounting options Modes: high beam, low beam and two flash modes Run times: 1.5 hours (high beam); 6.5 hours (low beam); 3.5 hours (high blink); 9 hours (low blink)