The Unitas 149 mechanical watch movement is an open face calibre with a bimetallic screw balance featuring four adjustment screws and a Breguet hairspring. It incorporates a negative stem mechanism and exhibits varying bridge shapes. While the exact differences between the 431 and 435 models are not known, the movement offers stem winding and setting functionality, as well as a sub-second display. This particular movement was predominantly used around the year 1949.