The original 1969 Mark II used Omega's Calibre 861 – a movement that tends to be very high-up on the wish list of any hardcore Omega collector. This more budget-friendly take on the cal. 321 was fully tested in the demanding environments of space (post-1969) and has proven to be a dependable workhorse across models like the Speedmaster Pro and orignial Mark II.

The new Mark II however uses the co-axial calibre 3330, an automatic movement with silicon balance spring and column-wheel chronograph mechanism (the 861 was the non-column wheel version of the 321, in case you were wondering). The silicon balance spring adds to the movement’s durability, and is something Omega has been using in other models as well, including the Speedmaster Racing.