Montre d'Aéronef 15-jewel WWII 1939-made Zenith Type 20 Cockpit Clock
Zenith Type 20 (Montre d'Aéronef Type 20) is a hand-wound clock for aircraft cockpits. A knurled bezel was used to wind and set the clock. Hand winding by turning the bezel. Montre d'Aéronef Type 20.