Limit pressure in your pipeline with the PVC Adjustable Inline Spring Check Valve, 1 in. IPS FPT X FPT. Allow water to flow one-way through pipe with its adjustable spring that is preset at 5 lb. and lifts when the water pressure exceeds the selected spring weight. This leak-resistant valve prevents backflow in your irrigation system. Connect two 1 in. MPT pipes with this check valve as part of a complete irrigation or other pressurized system. Prevents costly property damage, pipe corrosion, and system issues. Durable check valve is made of PVC plastic. Pressurized Spring is made of stainless steel. O-Ring is made of EPDM. Washer is made of neoprene. Use fittings and other valves to set up a new irrigation system, expand an existing system, or make repairs.