Sourcingbay Bike Chain Charger to USB - Dynamo, 5V 1000mAh for Cell phone /Tablet Charging (Black) Generator: AC Three-Phase Brush Less Material: Lightweight ABS Plastic Bicycle Chain Charger dynamo is a fully integrated ecological charging system for all your gadgets, phones or other devices! Built-in 1000mAh battery: If you often use your bike to commute to work, to school or on biking trips, this gadget is perfect for you. Using pedal power to generate power, this dynamo takes its power directly from the movement of your chain to charge its internal 1000mAh battery. Ecological way to charge your devices, power your phone and other gadgets on the road