Cal. 189 is one of a family of cam switching chronograph movements produced by Landeron. It is closely related to the preceding Cal. 48 and contemporary Cal. 148 but uses a conventional start/stop button rather than combining stop and reset and adds a date complication. The similar Cal. 149 lacks the date function.
The date is set by moving the hour hands past 12:00.
The Landeron Cal. 189 was famously used in the Heuer Carrera Date,