Salco Products (TC054PAH) 1/2-inch Stainless Steel Plug Assembly with Stainless Steel Chain consists of a plug that has 1/2-inch NPT threads, and is made out of 416 stainless steel material with a 3/16-inch seal hole drilled through the head. The width across the flats of the head is 1-inch. Length of the thread is .63-inches with the overall length of the plug being 1.34-inches. Comes with a stainless steel chain assembly that consists of a 1/4-inch, 304 stainless steel, swivel link that is crimped around the plug, and is connected to a 1/4-inch, 18-8 stainless steel, chain of 12 links.