Speecially designed to temporarily seal and stop off metallic or PE pipe remotely for fitting renewal or service line maintenance. Reusable, rugged, and lightweight made from Nitrile rubber and plated steel available in 1/2"-2” sizes. Also used as a tamper resistant night cap to prevent unwanted material such as dirt, water, debris, animals, etc. from entering open ended pipes. This is critically important when protecting your expensive pipeline projects. These pipe plugs are composed of two steel washers, which are compressed together by tightening the central bolt using the Special Expansion Plug Wrench.