This Is a 3660 3300KV 4 Pole 3.175mm 1/10 Sensorless Brushless Motor. (Include a 3.175mm to 5mm Reducer Sleeve). Those specially version motors have upgrade bearing and specially rotors to handle higher speed and great torque. Motor Is Great For Most 1/10 Scale Car And Truck Use For. 2S Lipo : On Road / Off Road 2WD And 4X4. 3S Lipo : 2WD And 4 X4. This Motor With 4mm Connector Please Check Your ESC Connector Size To Make Sure The Motor Will Fits Your ESC (Listing For Motor Only). Type : 4 Pole Sensorless. Max voltage: 2-3S Lipo 6-8 Cell Nimh. Shaft Diameter: 3.175mm (Include a 3.175mm to 5mm Reducer Sleeve).