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 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 show changes. It is suitable for DC brushed motors 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, the output of the speed controller can be connected 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 source 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 display differences may cause slight variations in color between the image and the actual item. Measurement error allowed is +/- 1-3 cm.