tapered polyethylene plug capsMOCAP tapered polyethylene plug caps are inexpensive dual function closures which can be used as either a plug or cap for either threaded or non-threaded applications. They are made from tough but flexible polyethylene to form a secure fit, yet they are easily removed, the company says. They’re recommended for use as a cap for tube and hydraulic fittings, tube end cap, pipe cap, product protection or for use as a plug for threaded holes, openings, fittings and ports.