This is the Traxxas Gray Velineon VX3 Cooling Fan

The ESC cooling fan reduces temperatures during extended operation for maximum power flow. It securely clips onto the Velineon VX3 heatsink for easy installation. Wires are neatly routed thanks to the integrated connector clip.

Simply plug the accessory cooling fan into the ESC accessory power connector and clip the fan onto the heatsink for increased cooling.