The A.J. Antunes 8021206060 SMD are compression fittings designed for use in HVAC equipment, particularly gas lines with pressures ranging from 0.17 to 12.0 inches of water column. They offer a secure and leak-proof connection for copper tubing sizes compatible with 1/8 to 1/4 horsepower motors. https://www.partshnc.com/8021206060-aj-antunes-smd-17-120-wc-comp-fit