QE QUALITY copper fittings are all detailed in nominal O.D. (outside diameter) sizing, compatible with R-410A refrigerant, and include C x C (copper to copper) connections. Construction WROT copper material, estimated temp. range: -20 to 400 degrees F, estimated max. pressure: 722 PSI @ 100 degrees F, and meet ASME, ANSI standards. Compliance certified.