Serfas Thunderbolt USB Taillight 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 35 lumens of pure red light USB rechargeable light, that fully charges in 3.5 hours Features 30-mini LED strip Features a water resistant silicone body and unique mounting options Modes: high beam, low beam and two flash modes Run times: 1.75 hours (high beam); 3 hours (low beam); 7 hours (high blink); 9.5 hours (low blink)