The Topeak Power Pack for Mega is designed for use with the WhiteLite Mega 10W lamp. A compact, lightweight and powerful Lithium Ion PowerPack is stem mounted via a strap to keep the cable routing short and steering sharp. The Topeak Power Pack for Mega provides up to 6.5 hours of run time with a charge time of 5-6 hours. Use as a backup PowerPack or as a perfect way to extend your nighttime riding time, the Topeak Power Pack for Mega adds more versatility to your already excellent lighting system. 5.5x2.2x4cm 32g