2Pcs 10A 12V-40V DC High Efficiency High Torque Current Protection control electric generator Motor Speed PWM Controller Knob Powered by RioRand advanced technology From left to right they are Motor-, Motor+, Power-, Power+ Working Voltage: DC 12V - DC 40V,Control Power: 0.01 - 400W Static Current: 0.02 A ( Standby ),PWM Duty Cycle: 10% -100% PWM Frequency: 13 KHz