PreTect thread masking plugs from PennEngineering protect internal threads of self-clinching nuts and standoffs during paint and powder coating processes. The pre-installed silicone masking plugs (supplied already in place) are designed for self-clinching blind standoffs, thru-hole standoffs, and nuts in thread sizes #4-40 to ¼-20 and M3 to M6.(…)
via Masking Plugs Protect Fasteners During Painting and Powder Coating.