... :1000mA Rachargeable battery:3.7V,300mAh Bicycle Dynamo Generator :Features:Bicycle chain drive the dynamo's gear to generate powerDynamo by bicycle ... for almost all kinds of bicycles The integrated design of dynamo, battery and voltage regulatorDIY installation, no need any toolsBuilt-in ... automatic adjustment holder(Patented), suitable for speed-variable bicycle Bicycle Dynamo Generator