Small, lightweight, and easy to mount - the Serfas USL-1 is the perfect solution for the daily commuter or the occasional night rider. Most states have laws that require you to have a light on your bicyle at night, don’t get caught without one. The USL-1 has a rechargeable Li-Polimer battery that willl charge quickly using your USB port, and give burn times up to 6.5 hours on a full charge.