Use in square thin or heavy wall tubing with an inner dimension of 1.5". Fully machined on our lathe and 4th axis mill for concentricity and ability to offer a low price. Threads are 1.25" - 12 tpi. Overall length of tube adapter is 2.375". Relief is cut along the length of the body to clear larger weld seams in tubing. NOW fully threaded to allow use of any length threaded joint. Tube inner dimensions may vary from manufacturer, shank of tube adapter is 1.375" +/- (.005).