Stores ref. 10A/12925. Fine cadmium plated gauze capping piece that fits over the backplate of the type 25 microphone within the type G mask. Approx. 5cm diameter.These were used to help prevent freezing of the microphone components at high altitude and later superseded with the introduction of the microphone heating element and rubber draught excluder. We have a small quantity available. Complete your mask and get one while stocks last! All in good used condition. Priced individually.