Description: This is a simple and easy-to-use DC motor speed controller of small size, elegant appearance and stable performance. It is made with high quality circuit board which ensures a longer service life. It support soft start, locked rotor protection, low voltage protection. Features: Speed controller is made with high quality circuit board which ensures a longer service life. This simple and easy-to-use DC motor speed controller has an stable performance. This motor speed controller uses screw terminals for convenient and quick wiring. Soft start function would protect speed controller and motor against damage from large instant current. It supports locked rotor protection by limiting large current(maximum 30A) instead of cutting off power. If you use a storage battery as power supply, the low voltage(10V) protection function would prevent over-discharge. Specifications: Input Voltage: DC10V-55V Output Voltage: Linear with load Output Current: 0A-40A Limit Current: 30A Speed Range: 0% to 100% Regulation Method: Potentiometer(Linear, 270) Control Frequency: 15KHz Wiring Type: Screw terminal Rotary Knob: 10K(with switch) Size: 80 x 56 x 28mm / 3.15 x 2.2 x 1.1" Package Includes: 1 x Speed Controller