For use in both pipe end and cleanout threads. Polypro wingnut, nylon top plate, soft PVC (polyvinyl chloride) gasket and nylon base/stem for simplicity and strength. Provides a leak-free seal at over 8 times the P.S.I. of other mechanical test plugs. Back-to-front wedge design prevents blowouts at high and low temperatures. Nonslip shoulder for fast, easy installation. 100% non-corrosive.