This John Guest imperial single check valve is made of acetal copolymer and has tube connectors. This imperial single check valve is suitable for use with liquids. It restricts the flow of liquids and other loose materials to one direction through a pipe or passageway. It is a push-to-connect fitting that accepts the insertion of nylon, soft nylon and polyurethane tube fittings. It is made of acetal copolymer plastic, which has low moisture absorption, high tensile and flexural strength, and is hard and fatigue resistant. The working pressure for this fitting is up to 145 pounds per square inch (psi). This fitting meets National Sanitation Foundation (NSF)/American National Standards Institute (ANSI) standards 14, 51, and 61 for plastic piping systems, food equipment materials, and use with drinking (potable) water.