The Speedmaster's history goes back to 1957 when it was introduced as a sports and racing chronograph, complementing Omega's position as the official timekeeper for the Olympic Games.
The "Speedmaster" name was chosen for its tachymeter scale bezel and following the Omega convention used for other models like the Seamaster - initially, the Speedmaster was part of the Seamaster line - and the Railmaster.
This example is from late 2021 and features the manual wind cal 3861 movement. The Caliber 3861 uses the Lemania 1873 as its base just like the standard Moonwatch with caliber 1861 but features a power reserve of 50 hours when fully wound.
The goal of the cal 3861 was to make a Master Chronometer Certified upgraded version of the 1861. It took Omega 4 years to develop and they did achieve a METAS Master Chronometer Certification.