Stores ref. 5D/527. Brass connector used in conjunction with other oxygen equipment and at one end of the MK.III Oxygen tube adaptor used to enable the use of E-series, G-type and H-type masks in older aircraft fitted with early oxygen systems. These adaptors were also used to connect masks to portable (walkaround) oxygen bottles. The connector is Air Ministry stamped. Some tarnishing and wear. The internal spring has rusting but functions correctly. Found on the old RAF station site at High Ercall in Shropshire. Stock code O18200.