it is (was) a poor-man's chronograph. With the pusher the balance can be stopped and released, and accordingly the sweep second hand, which is gone at some point. Here a description of the movement: bidfun-db Archiv: Uhrwerke: Baumgartner 677
Looks like a "Chronostop"; the buttons move the lever you see in the middle of the movement, which has a finger on it that presses against the balance wheel to stop it. This allows you to use the second hand of the watch (which is missing, by the way) as a sort of crude stop-watch (note that stopping the second hand stops the entire watch, so...)
A forum community dedicated to watch owners and enthusiasts. Come join the discussion about watch collections, displays, watch winders, accessories, classifieds, and more! We welcome all manufacturers including Casio G-Shock, OMEGA, Rolex, Breitling, Rolex and Tudor, Seiko, Grand Seiko and others.