The Bettlach 8400-73 watch movement, often signed as AS 1290, features a unique wheel placement between the barrel and minute pinion, allowing for the barrel and center-second wheel to be on the same layer. As a result, the base movement remains relatively thin, despite the presence of a sweep second. Additionally, the revolution direction of the barrel is changed, necessitating an additional wheel in the winding gear. This movement offers manual wind functionality and includes a sweep second, day, and date complication. It was commonly used around the 1950s.