Approved to be used underground and behind walls without access panels. Fittings are certified to 200 PSI and 180° Fahrenheit (82° Celsius). Integral tube liner for PEX installations which means no loose connections. Made of DZR (dezincification resistant) brass which provides a strong, durable fitting that is corrosion resistant. The SharkBite design is certified to ANSI/NSF-61 and ASSE 1061 product standard for use in potable water and hydronic heating water distribution. Designed for hydronic heating as well as potable water distribution. Please consult your local plumbing codes for specific applications.