Features The speed controller fits the DC brush motor. Simply adjust the motor speed via the external potentiometer. Original chip and specially adapted silicon controlled rectifier. Dual layer military grade PCB design. Maximum power up to 2000W. Specification: Item Type:DC Motor Speed Controller Input voltage: DC9-55V. Output voltage: linear under load Output limit current: 40A (20A for long time, be sure to keep the module under unobstructed heat dissipation conditions) Ultimate Power: 2000W Speed control mode: potentiometer (linear) with switch. Speed control working range: 0-100% Control frequency: 25 kHz. Button wire length: 20 cm / 7.87 inches. Motherboard mounting size: 85 x 58 x 38 mm / 3.35 x 2.28 x 1.5" Mounting hole for potentiometer: 7 mm / 0.28 inches. Item Package Weight:130g Item size: 8.5 x 6 x 3.9 cm / 3.35 x 2.36 x 1.54 inches. Package weight: 138 g Package list: 1 x motor speed controller. 1 x button cover. Small tip: Before switching on, make sure the positive and negative connections are correct. Do not touch the heat sink with the wiring as this may burn the board. Note that this is not a power supply module. It must be connected to the motor to adjust the speed. The output of the multimeter does not change without the motor. It cannot be connected to the AC brush motor. Package List 1 x Motor Speed Controller 1 x Knob Cover