The Longines 6641 watch movement, produced from 1961 to 1963, features a ball-bearing rotor with a peripheral gear out of center, optionally equipped with 5 ruby balls. It incorporates a rather large balance, along with a ratchet on the dial side and a crown mechanism with a rocker bar. This mechanical movement offers automatic winding, sweep second functionality, and a date function that can be set by changing the time between 22:30 and 24:00 hours.