Lemania 321

The Cal. 321 is a manual-winding chronograph movement manufactured by Lemania for Omega. Based on the Lemania 2310 (27mm diameter, 6.74mm height), it powered the Speedmaster Professional references ST105.012 and ST145.012 from 1957 to 1968. The movement was the first chronograph to pass NASA's tests for crewed space missions, earning it the "Moonwatch" designation. Omega replaced the 321 with the Cal. 861 in 1968 but re-released it in 2019 for vintage-style reissues.