The John Guest PSEI4628 is a 3/4-inch end cap. This quick-connect, lead-free fitting is both safe and easy to install and can be used to connect copper, PEX, and even CPVC pipe. It is made of high-quality material that ensures it is resistant to corrosion and prevents build-up formation. This durable push-fit end cap is for use with hydronic heating and hot and cold water. It can also be used to test the pressure of a system before connecting the appliances, saving you time and energy. This cost-efficient John Guest PSEI4628 can be installed without the need of any special tools, just push and you're good to go! It comes in a pack of 5. Please take note that it should not be used for fuel, gas, or compressed air applications.