Prevent water from flowing out the end of your tubing with the 1/2 in. Compression End Cap. This fitting works with 1/2 in. distribution tubing or dripline, and has a removable cap to flush out the line as needed or to expand your system. Tubing fits into the compression ring, where an internal barb compresses the tube. Got tough tubing? Try softening the tubing material by soaking the ends in hot water or leaving them out in the sun. The compression end cap is made of acrylonitrile butadiene styrene (ABS), a type of plastic, treated with UV inhibitors to prevent cracking.