Direct water flow one-way through pipe with the PVC Spring Check Valve, 2 in. IPS FPT X FPT. Water is allowed through the valve when the water pressure is greater than the weight of the 1/2 lb spring. This leak-resistant valve connects two 2 in. MPT pipes in an irrigation or other pressurized system and prevents the backflow of water. Prevents costly property damage, pipe corrosion, and system issues. Durable check valve is made of PVC plastic. Pressurized Spring is made of stainless steel. Washer is made of EPDM. Use fittings and other valves to set up a new irrigation system, expand an existing system, or make repairs.