L.H. Dottie 4 Inch Zinc Plated Steel 3-Piece Knockout Seal

Three Piece Knockout Seals are used to cover exposed knock-out holes in metal enclosures or outlet boxes. They are held in place by a screw inserted through the seal into a threaded strap on the opposite side of the opening. They are able to installed from the inside or outside of any box without rearranging wires.