Foxnovo Durable Aluminum Alloy Heatsink Heat Sink with 5V Cooling Fan for 110 Car 540 550 3650 Size Motor Color: mainly blue. Material: durable aluminum alloy and hard plastic. Cooling fan size: about 30*30*10mm. Suitable for 110 Car 540 550 3650 Size Motor. Come with a 5V cooling fan to protect your motor. The cooling fan can power up from the receiver, very easy to use.