very old (1910-1920ies) Aron single phase meter 3 Amps, 225 Volts 50 Hertz, two digits decimal reading. Thes ewere very common in the early days of electricity at home. These were only able to handle about 700 Watts but for the few lightbulbs at that time, this was sufficient. This particular one was repaired/refurbished in 1949 by PFN (Paul Firchow Nachfolger) in Frankfurt.