These CTS AquaLock plastic end caps work with copper, CPVC, PEX, and CTS rated pipe. They are easy to install, no tools or tube inserts are required. These fittings can be used for hot and cold water applications. Their unique O-ring guide feature provides a zero-leak connection. Unlike barb fittings, these fittings joins the tubing on the outside, increasing the flow capacity. After a connection has been made even under maximum pressure, the tubing is able to swivel, making the fitting ideal for vibrating and dynamic applications.