Salco Products (TC075PA) 3/4-inch Carbon Steel Plug Assembly with Carbon Steel Chain consists of a plug that has 3/4-inch NPT threads, and is made out of carbon steel material. The width across the flats of the head is 1-inch. Length of the thread is .625-inches with the overall length of the plug being 1.06-inches. Comes with a carbon steel chain assembly that consists of a 1/8-inch, carbon steel, swivel link that is crimped around the plug, and is connected to a 3/16-inch, zinc plated carbon steel, chain of 12 links.