The A Michel 320 is a mechanical watch movement that was produced from 1937 to 1970, with over 3.5 million units manufactured during that time period. This movement was utilized in a range of chrono mechanisms, and due to their interchangeable parts, occasionally series were produced with components from different calibers. The A Michel 320 shares minor differences with the Landeron 81, and modified parts can be interchanged between these calibers. Additionally, the A Michel 320 features a manual-wind chronograph with a 60-second counter, as well as a 30/45-minute counter that is cam switched. Other functions include sub seconds, a tag function with a pusher at 10 o'clock, a date hand with a pusher at 9 o'clock, a month function with a pusher at 2:30 o'clock, and a moon phase function with a pusher at 8 o'clock.