The Poseidon Cyklon special regulator hose is not compatible with a standard second stage fittings. Supplied by OmniSwivel International, this adapter has a unique Cyklon male fitting on one end and the other end has an industry standard 9/16-18 UNF female fitting on the other end. This adapter will mate with the unique female fitting found on the end of a Poseidon Cyklon 60 special hose and then mate with any standard 9/16-18 UNF male fitting typically found on most second stages.