Cavagna Type 1 ACME Nut Pigtail. Pigtails are used with double stage automatic changeover regulators for two cylinder systems or standard double stage regulators with T-check connections. UL listed assembly, CSA approved hose. Hang tagged for store display. Safety features: Excess flow device: Limits gas flow in the event of hose rupture or accidental disconnection. Thermofuse: A heat sensitive plug, which shuts off gas flow if temperature reaches above 240 degrees F. Type 1 ACME Nut x 1/4 inch Inverted Flare. 15 inches L.