The Neptune Advanced Stroke Controller allows the capacity of any Neptune 500 Series, 600 Series, or 6000 Series Hydraulic Metering Pump to be automatically controlled in response to a standard 4-20 mADC process signal. The one-piece controller-positioner mounts directly to the pump. No machining or any special drillings or tapings are needed to retrofit the pump. The Advanced Stroke Controller is commonly used in water/wastewater, power and process industry applications or anywhere pump flow must be automatically proportioned or varied.