Carbon granule microphone compact model

To demonstrate the operation of a carbon fiber microphone, when the box is pressed together with the fingers, the resistance value of the “microphone capsule” changes;
Transparent elastic plastic box, filled with carbon granules, tightly closed with lid, two 4 mm sockets firmly mounted on the side to accommodate 4 mm safety plugs
Dimensions (without sockets): 65(105) x 48 x 22 mm
Mass: 69 g