The Bettlach 8401-73 is a manually wound mechanical watch movement that features a pin lever escapement. It includes a ratchet on the dial side and a crown mechanism with a rocker bar. The 051/03 is part of a series which includes variations like the 051/01, 051/03a, 051/04, 051/04a, and 051/04e, with only minor differences among them. This movement was commonly used around the year 1955 and offers functions such as manual winding and a sub second display.