Stores Ref. 10A/10989. This consists of an extremely rare electro-magnetic microphone, type 18 (stores ref. 10A/10990), complete with wiring loom and plug. The type 18 microphone is of course the 'flat-fronted' chamois covered pattern introduced in January 1939 and used in conjunction with the D-type oxygen mask throughout the Battle of Britain. By October 1940 the type 20/type 21 assembly had been introduced so the type 18 had a relatively short production run. The microphone is in quite good condition retaining excellent original one-piece chamois covering. The rear aluminium screw-on cap is missing revealing the wax insert that would not normally be seen. This special wax composition has a melting point over 120 degrees centigrade and is used in order to raise the resonant frequency of the instrument to above 2,000 cycles per second. An 'off-off' switch , operated by a small serrated disc (missing) is mounted within a bakelite and paxolin assembly at the lower side of the microphone. Whilst the switchgear and paxolin are original, the left side section of bakelite has been carefully replaced as this was missing. See photographs for details. The mid tan wiring loom and early brown cased jackplug are both in excellent condition (although the loom is actually a later example than would have been originally fitted - I can supply the correct loom in place of this for the buyer if required). An Air Ministry Order actually called for the removal of the serrated disc switch knob to prevent accidental turning off of the microphone and most 18's are found with this piece missing. Overall this is a superb item ready to for mounting to a type-D oxygen mask. Don't miss this one! Stock code O14706.