1. Good heat dissipation performance ensures safe and efficient work. 2. It can effectively help form better air channel and improve improve the effect of heat dissipation . 3. Equipped with 5V cooling fan, practical for protecting the motor from overheating. 4. It has perfect heat dissipation effect which can effectively prevent the motor from overheating. 5. Easy and convenient to install and remove. Specification: Condition: Item Type: RC Motor Radiator Cooling Fan: DC5V Applicable Motor: for 540 550 3650 motor Motor Fan size: 30mm x 30mm x 10mm Colour: Material: aluminum alloy + plastic Package Contents: 1 x Motor Heat Sink 1 x Cooling Fan Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.