Create a watertight connection in your drip system tubing with the 5/8 in. Compression Coupling. Use the coupler to join two sections of 5/8 in. supply tubing or dripline together. To install, insert the end of the tubing into the compression ring where an internal barb compresses the tube with a firm grip, and repeat on the other end of the fitting. Durable and weather resistant, the compression fitting is made of acrylonitrile butadiene styrene (ABS) treated with UV inhibitors to prevent cracking.