Landeron 48

The Landeron Cal. 48 was a groundbreaking cam-switching chronograph movement, succeeding the Cal. 47 as the world's first commercially successful cam-actuated chronograph. Produced from 1937 to 1970 with over 3.5 million units manufactured, it featured a distinctive curved hammer design. The movement uses Heuer-style oscillating pinion chronograph activation. Notable for its unconventional two-button operation where the 2:00 pusher starts and the 4:00 pusher stops and resets.