What is it? Our check valves are crafted from polypropylene. It employs push-to-connect technology, enabling users to connect and disconnect quickly and easily without the need for any additional tools. Normally, it allows liquid to flow through in only one direction without leakage and is extremely easy to install. It is compatible with standard 1/4 inch outer diameter plastic RO tubing, copper, CPVC, PEX, and PVC pipe or hose. Where to use it? Applications include RODI systems, irrigation systems, refrigerator ice maker tubing, coffee machines, and more. How to use it? Simply insert your tubing into each end by pushing until it cannot go in any further. To remove, just push the outer circle on each end and pull it out directly. Ensure that the tubing is cut smoothly to guarantee no leaks. Make sure you cut the tubing evenly and straightly without crimping it. Then insert it straight and all the way into the connector. If it is crooked, not inserted fully, or crimped, it may leak. What you will receive? 5 pieces of 1/4 check valves.