Quick connect or coupler with 5/8UNF connection. Attaches to Regulator or Flowmeter outlet. Quick connect/disconnect. Shuts off when disconnected - doesn't lose valuable Argon gas! GREAT TIME SAVER - just hit the button and it's off - no need to find a spanner at the end of a long day to put your welder away! Makes it EASY to shift your Welder around the site.Custom made by us. REC21PG6NIP goes into this coupler. The hose goes onto a REC21PG6NIP.