Salco Products (TC0254PA) 1/4-inch Stainless Steel Plug Assembly with Stainless Steel Chain consists of a plug that has 1/4-inch NPT threads and is made out of 416 stainless steel material. The width across the flats of the head is .62-inches. Length of the thread is .38-inches with the overall length of the plug being .75-inches. Comes with a stainless steel chain assembly that consists of a 1/8-inch, 304 stainless steel, swivel link that is crimped around the plug, and is connected to a 1/8-inch, 18-8 stainless steel, chain of 12 links.