Yiguo Alloy Heatsink with 4.8-6V Cooler Cooling Fan for 1/10 Car 540/550 Size Motor Gray 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