Gardner Bender KO702C Metal Knockout Seal, &frac34;  Inch Conduit Size, Marked Size, Rust-Proof Galvanized Steel, 16 AWG Steel,  Inch Thread, Embossed - Self Centering, For Knockout Punch / Die Conduit, Cover, 3 Pk. Easy-to-use metal knockout seal Superior quality at an affordable price Embossed for quick self-centering in unused knockouts