Seal off the end of your tubing with the 5/8 in. Compression End Cap. Connect to the end of 5/8 in. distribution tubing or dripline to stop the flow of water; removable cap makes it easy to flush out the line as needed or to expand your system. To fasten, insert the tubing into the compression ring, where an internal barb compresses the tube. Having trouble getting the tubing to fit? Try softening the tube ends by soaking in hot water or leaving out in the sun. The compression end cap is made of acrylonitrile butadiene styrene (ABS) treated with UV inhibitors to prevent cracking.