Serfas" Thunderbolt Taillight gives you style and safety in one high-powered and affordable package. Being seen on your bike at night never looked so good until Serfas" Thunderbolt Taillight hit the scene. This USB rechargeable gem comes with 35 lumens of firepower while giving riders" several different rear facing mounting options. The 30 micro-LED strip will let your presence be known to cars and bikes alike. The rechargeable Lithium Polymer battery will have you saying good bye to buying additional batteries and hello to saving the earth and all your hard earned money. Charge up, light up and get riding safely with the Thunderbolt. Below are the burn times for the UTL-6BK Thunderbolt Taillight. Steady High = 1.75 Hours Steady Low = 7 Hours High Blink = 3 Hours Low Blink = 9.5 Hours