7-70V 30A PWM DC motor speed controller, can be directly connected to the motor and adjust the potentiometer to adjust the motor speed. Instructions and precautions: Make sure the positive and negative connections between the power supply and the controller are correct before powering on. Reverse connection may burn the circuit board. Do not touch the heat sink with the wires, as this may burn the circuit board. (Motor) It is not necessary to distinguish between positive and negative poles. If the direction of rotation is wrong, you need to swap the two wires of the motor. Please note that this is not a power supply module, it must be connected to the motor to adjust the speed. Without the motor, the meter's output will not change. It is suitable for DC brushed motors and cannot be connected to 220V household power. Used for children's toy cars. If the product is used to modify children's cars, the output end of the speed controller can be connected to a forward and reverse switch to achieve the function of forward and reverse control. If there is a forward and reverse controller on the children's car, be sure to connect the speed controller in front of the forward and reverse controller (in other words: between the power supply and the forward and reverse controller) on the children's car. Otherwise, the speed controller may be damaged. Specifications: Condition: 100% new Material: Aluminum Color: Black + Green Package Contents: 1 x DC Motor Speed Controller 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 +/- 1-3 cm.