Estimated Date: 1920
Description: 1” circular x 1.75” bell shaped bell with cone inset and U shaped metal tube connected to C shaped tube attached to bell. Rubber tubing connects to U and than to usual metal binaural earpieces with ivory ear plugs. The earpieces can be folded, the tubing is 18” long and the heavy 0.5” diameter (black) of the period.
Reference 1: 37