MTM Hydro Zinc Plated Steel Plugs are an economical solution for QC conversion. When selecting a size, be sure to match with a coupler of the same size. i.e. 1/4" Plugs can only be received by 1/4" couplers.
To upgrade, see the selection of MTM Hydro Stainless Steel plugs and couplers which will help resist corrosion and rust.