single all original and nicely aged antique american 19th century exterior residential entrance door flush mount doorbell likely fabricated by or for the p. & f. corbin company, new britain, ct. the interior hammers are typically actuated by turning a knob or thumbtwist to ring the bell or "gong." the cast iron base plate retains the original baked-on black enameled finish. the unornamented solid bronze bell has a nicely patinated original nickel-plated finish. the knob or handle is mounted on the exterior side of the entrance door. the bell is mounted flush against the interior side of the entrance door. measures 6 x 4 3/4 x 2 1/2 inches.