Flair-It 1/2 PEXx1/2 PEXx3/8 PEX Tee. It is compatible with PEX or polybutylene pipes. Made from durable Polyoxymethylene material, this tee is resistant to stress fractures and extreme temperatures. It has a maximum working pressure of 200 psi and a maximum working temperature of 200°F. It is corrosion resistant, Lead-Free, removable and underground use. Installation is easy - cut the tubing square, slide the nut along the tubing, rock the fitting all the way into the tubing, slide the nut back onto the fitting and tighten it as far as it will go. FLAIR-IT fittings meet cNSF-14pw and NSF-61 and are manufactured to ASTM standards F876/F877 and CSA 137.5 specifications. It is THC warranted for 25 years from the date the pipe, fittings and valves shipped out of factory when operating within allowable pressure and liquid, heat transfer liquid leakages result from manufacturing defect.