Tri-Clamp to Male NPT Lids - 2"x1/2" - These end caps, often called lids, convert from tri-clamp to a male NPT thread. On the 1/4" lids, the threads go all the way through to the button of the lid so that you can add fittings to the top and bottom of the lid. These lids are made from 304 stainless steel and come with a high-polish finish.