Use this Barb x MPT Flow Control Valve as an On/Off device to control the water flow in low pressure irrigation systems. Valve coupling has 1/2" male pipe threads and a 16mm barb that fits 1/2" tubing with .570 to .620 inches inside diameter. Features: Simple on-off operation and straight through flow Operating pressure range up to 45 PSI Green Back cap for standard irrigation applications Purple Back cap for recycled water applications UV stabilized materials for long life