This is a wall carbon microphone in a square wooden box (15.5 x 15.5 x 3.5 cm) which derives from Hughes' microphone, from which it differs only in that instead of the carbon cylinder, it has a capsule full of carbon granules.
On the square face of the box we see: in the centre a large, round, metal flange containing the capsule of carbon granules and on the outside the housing of the microphone; below this is a metal tag with the name of the manufacturer and above the two clamping screws for connection in series to a battery of accumulators and, across the line, to the receiver.