7-70V 30A PWM DC Motor Speed Controller, can be directly connected to the motor and adjust the potentiometer to control the motor speed.Instructions for Use and Precautions: Ensure that the positive and negative connections between the power supply and the controller are correct before turning on the power. Reverse connection may damage the circuit board. Do not touch the heat sink during wiring, as it may cause damage to the circuit board. For the motor, there is no need to distinguish between positive and negative terminals. If the rotation direction is incorrect, swap the two motor wires.Note: This is not a power supply module; it must be connected to a motor to adjust speed. Without a motor connected, the multimeter output will not change. It is suitable for DC brushed motors only and must not be connected to 220V AC household power.Application in Children's Toy Cars: If used in modifying a children's toy car, connect the output end of the speed controller to a forward and reverse switch to enable forward and reverse control. If the toy car already has a forward and reverse circuit regulator, connect the speed controller between the power supply and the forward and reverse regulator (i.e., before the regulator). Failure to do so may result in damage to the speed controller.Specifications: Condition: Material: Aluminum Color: Black + Green Package Contents: 1 x DC Motor Speed Controller Note: Light reflection and differences in display screens may cause slight variations in color compared to the actual item. Measurement error allowed is +/- 1-3 cm.