------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Motor supportReversiblerunningand has more noise when reversed running than normal running, this is a normal phenomenon, please know before buying.--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------We offerCustomized Speedservice. And only we can offer so much speed for choosing. (If you buy our controller, and want A rpm speed, so can adjust speed from 0toArpm, Such as 12v 6rpm, can adjust 0-6rpm) Note: please buy according to Max Efficient torque(rated torque) , Stall torque is just as a reference. Because if the load is above rated torque, it may damage the gear of motor.Such as, if the load of your project is 55kg, we suggest 12v 16rpm(rated torque 60kg.cm), not 12v 32rpm(rated torque 50kg.cm).