Planet Bike Dynamo 2.4-Watt Krypton Bulb Bicycle Headlight Hub-driven headlight with 2.4-watt krypton bulb Powered by wheel hub for battery-free riding Integrated on/off switch to reduce hub resistance Intelligent circuit works with 2.4- and 3-watt dynamo hubs Compatible with linear pull, disc, and drum brakes; limited lifetime warranty