Radio Compass Indicator, Pre-WWII
Here is a fine example of an early Radio Compass Indicator, and based upon our knowledge of designs of the era, we estimate that it is pre-WWII or early WWII era. It is a Weston model 602, Type 59.
The radio compass, receiving ground signal from a selected transmitter via its loop antenna mounted top or bottom of the fuselage, provided directional indication (left or right) to the pilot with respect to the source of the signal.
The indicator is in exceptional condition give its age. The seal around the glass is absent, but doesn't affect the cosmetic appearance and could be replaced. Measures 3.25 inches diameter and ~2 inches deep.