This Steel Snap-In Fitting for MC Cable, is for use in 1/2 in. knockouts with 14/2 to 10/3 steel and aluminum cable. Made of electro-zinc plated steel, with a 0.84 in. Dia Removable and re-usable. There are no set screws, locknuts or tools required. For use with 14/2 - 10/3 MC Cable.