FLAIR-IT Tee is a compression fitting that is compatible with PEX or polybutylene. Made of durable polyoxymethylene material, it resists stress fractures and extreme temperatures. 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. Use manufacturing part #06790, PB Adapter Sleeve, when using FLAIR-IT fittings with 3/4 inch Polybutylene pipe.