Carbon granule microphone, compact model

Demonstrates how a carbon microphone works: when the box is squeezed between the fingers, the resistance of the “microphone capsule” changes. Transparent, elastic plastic box filled with carbon granules and tightly closed with a lid; two 4 mm sockets firmly mounted on the side accept 4 mm safety plugs. Dimensions (without sockets): 65 (105) x 48 x 22 mm; mass: 69 g.