Stores reference 10A/11994. Black painted alloy microphone, often referred to as the '1941' pattern although it was actually introduced in October 1940. Also known as the 'type 21', but this is the reference allocated to it when fitted to a wiring loom. The casing of this example is somewhat distorted and paint chipped but alloy is quite easy to reshape. The small closure tab riveted to the top of the casing is absent. Air Ministry and King's crown markings. Parts of the inner rubber band remain but are hard/perished. With remnants of the original wiring loom. The type 20 microphone was mainly used in conjunction with the type D cloth oxygen mask. A fair used example. Stock code O4601.