1/4" ID FEMALE X 1/4" ID FEMALE COUPLING;The NDL ACR Copper Fittings Series, with increased weight;has been especially designed for commercial refrigeration;and HVACR systems, providing excellent fit & finish,;as well as economy of joining. ;NDL ACR Copper Fitting Series is manufactured to the ASME;B16.22 Standard, sizes are marked on fittings.