Use in square thin or heavy wall tubing with an inner dimension of 1.25". Fully machined on our lathe and 4th axis mill for concentricity and ability to offer a low price. Threads are 7/8" - 14 tpi. Overall length of tube adapter is 2.0". 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).