3RACING Aluminium Case High Speed Cooling Fan, comes with 2 sizes #3RAC-FAN10 - 30 x 30 x 10mm & #3RAC-FAN11 - 40 x 40 x 10 mm. - Aluminium case indeed is more durable but it could also use as a heatsink and with the high speed fan it can increase the cooling efficiency of the cooling system. - Useful accessory to reduces ESC or Motor temperatures! - 2-pin receiver connector plug for fast and easy connection! - Aluminium black color case with bronze highlight to create a clean and strong look!