This heat sink is a professional and practical heatsink , fit for 540 550 and 3650 3660 3670 motor , it will come with a 5V cooling fan, this cooling fan can power up from the receiver to protect your motor, very easy to use.Material: Aluminum Alloy Hard Plastic RC Electric Motor Heat Sink upgrades for 1/10 Slash, Stampede, Rustler, TRX4, A-xial SCX10, Tamiya CC01 , Redcat GEN7 etc.RC Truck Crawler Buggy.Aluminum RC Motor Heatsink is CNC machined, it can be easily remove and install by hand.Package Includes: 1 x Motor Heatsink, Aluminum RC Motor Heatsink with Fan