Product details:

Oil-tight Knockout Seal with Gasket - Garvin Industries - 4 in gasketed stainless steel, oil tight knockout seals are inserted in discontinued, open box knockouts to protect exposed wires on stainless steel enclosures and cabinets. The 316 Stainless steel material and gasketed closure plate allows the installer to prevent oil, water, dust, dirt and debris from entering live electrical panels through unused knockout openings. Electrical Junction Boxes, Installation Accessories, Stainless Steel Oil Tight Knockout Seals | Panel and Pulling, Knockout Seals, Three Piece Stainless Steel | Stainless Steel Products, Conduit Boxes, Knockout Fillers, Garvin Industries, Stainless Steel 4 in.