Mask/microphone heater. Stores reference 6D/909. This was clipped on to the mask-side of the type 26 microphone within a type G mask, and designed to prevent icing over the microphone, reduce risk of freezing of the mask valves, and increase comfort when wearing the mask at very low temperatures. It is a simple resistance type of heater, rated at 4-5 watts at 24 volts, contains no switch, being turned off by separating the plug and socket. The heater is wired to a 2-pin plug ref. 5c/455. The heater is in good overall condition but does has some light soiling, verdigris and corrosion on metal parts. The short rubber covered loom remains quite flexible but does have some cracking and is part-severed. Wired to a very good 2-pin plug. Extremely rare to find as only in use for a very short period. Stock code O21297.