This is a chrome voltmeter by Hartmann & Braunn . The scale is zero to 20 volts.  Blue/green glass with a white paint dial.  The mechanism is a moving coil style with spring balance.  Ideal for direct current measurements.  Can be set to 5v scale or 20v scale.

The condition is excellent.  There is a dent on one side as well as a damaged finish spot.  The finish is mirrored chrome.  See pictures. The meter is fully working and deflects accurately.  The needle is medium speed, and quite ordinary for moving coil galvanometer style meters of this era.

Fast, careful shipping.