A not-often-seen brand with a non-often-seen complication. The Mono-Rattrapante function allows for two events to be timed concurrently. With the chronograph running, the bottom pusher can be pressed at the completion of event #1 to stop the progress of the sweep hand, which allows one to observe the elapsed time on the chronograph. Once the bottom pusher is released, the sweep hand jumps forward to resume timing event #2.
Unrestored, original condition.
Valjoux 84 movement is keeping time but service history is unknown.
Rattrapante function works as it should.