Plastic tees can either allow 2 tubes to flow into 1, or 1 tube to flow into 2. Polysulfone Push-Fit Fittings install without tools or locking clips. They are reusable and compatible with metallic to soft vinyl tubing including copper, CPVC, and PEX. Certified for use in potable water applications. CTS Twist-and-Lock Fittings are suitable for use with cold and hot water distribution, potable water distribution, and hydronic heating systems.