Compression fittings have an internal compression ring that squeezes the outside diameter of the tubing as it is inserted into the fitting. Once the tubing is inserted into the fitting it is very hard to remove the tubing.Compression fittings are among the most common connection style fittings used in drip irrigation systems to connect sections of either 1/2 or 3/4 solid drip irrigation tubing or dripperline.
A nipple is a short piece of pipe with male pipe threads at both ends..1/8 Inch x 6 Inch Galvanized Nipple They are commonly used for outdoor and industrial applications.