DC speed controllers are ideal for slowing down pumps and motors or dimming lights but commonly use resistance circuits and are very inefficient. The pulse width modulation (PWM) used in this controller allows you to vary the output from 0 to 100% while maintaining a very high efficiency. When used on motors this ensures full torque is available at very low speed and the motor won't shudder at start-up. Operates on any 12VDC system and capable of controlling devices rated at up to 8 amps. The internal circuitry is fully potted and the control potentiometer is splash proof making this suitable for marine environments and other harsh conditions.