http://www.modelsport.co.uk/?CallFun...n&ItemID=30589
http://demonpowerproducts.co.uk/prod...oducts_id=1779
you need the 2cell model NE5470
you solder the black and red wires to the battery wires on the speedo then plug the speedo into the smart stop, then the smart stop into the reciever.