The Omega 591 is a mechanical watch movement introduced in 2002. It features an automatic chronograph function with registers for measuring 60 seconds, 30 minutes, and 12 hours. The movement incorporates a pillar wheel mechanism for smooth operation. Additionally, it includes a flyback feature allowing for instant reset and restart. Other functions include a sub-second display, a day indicator set through a pusher located at 7:30 o'clock, a quickset date function, a month indicator adjusted via the date, and a moon phase complication set by a pusher positioned at 8 o'clock. The Omega 591 movement was utilized from its introduction in 2002.