Feature12000- 20000 RPM Gearbox with 6V/ 12V Drive Engine, RS390 Drive engine is made of high strength plastic board combined with high quality motorHigh SpeedRide on gearbox is specially customized for Kids Carriage modification, car modification with High Speed.You can also adjust the speed, but the electric gear motor speed can only be reduced, can not be raised. Low noise and high torqueField of useGearbox is used in the majority of wheels, is suitable for cars, remote control cars and motorcycles, ATV, karting, child vehicles and other modifications. It is a good choice to replace the broken oneEasy operationGearbox Item is easy to replace and is universal, guaranteed Exact Fit for easy installation, engineered for superior durability, backed by industry warrantyKindly RemindCheck the size of the gear before purchasing. There are Four type : Type(Optional): 6V 18000RPM, 12V 12000RPM, 12V 16000RPM, 12V 20000RPM, Total length: Approx. 16.5cm / 6.5inch, Hole Diameter: 1cm / 0.39in, Weight: approx. 270-289g. Please note thta the new type and old type of this product will be sent randomly, and make sure you will not mind before ordering.