SW510 M a

Cam-actuated two-button manual chronograph. Tracks hours, minutes, and small seconds at 9 o'clock, with a central 60-second hand, 3 o'clock 30-minute counter (optional 15-minute as SW511 M a), and 6 o'clock 12-hour counter. Features quick-set date, manual winding, stop-seconds, 28,800 vph (4 Hz), 23 jewels, and a 63-hour power reserve.