RC Aluminum Heatsink 4.8-6V with Fan Cooling for 540/550 Model Car Motor Blue 540/550 Aluminum Motor Heat Sink and Cooling Fan, 4.8-6V cooling fan to protect your motor The cooling fan can power up from the receiver, very easy to use. It is replacement part for RC 1:10 Car 540 550 Motor Heatsink It is made of Aluminum Alloy and Plastic combined with fan cooling