![Ron Gordon Watch on X: "Omega caliber 1861 (base movement Lemania 1873) is a manual-wind chronograph, has a switch cam - 18 jewels and rhodium plated. https://t.co/fq12R5JQ4N" / X Ron Gordon Watch on X: "Omega caliber 1861 (base movement Lemania 1873) is a manual-wind chronograph, has a switch cam - 18 jewels and rhodium plated. https://t.co/fq12R5JQ4N" / X](https://pbs.twimg.com/media/FsvjksyXoAAzw_Z.jpg)
Ron Gordon Watch on X: "Omega caliber 1861 (base movement Lemania 1873) is a manual-wind chronograph, has a switch cam - 18 jewels and rhodium plated. https://t.co/fq12R5JQ4N" / X
![File:Detailed view on chronograph pushers and crown (with open watch movement) of an Omega Cal. 1861 chronograph movement from an Omega Speedmaster (cropped).jpg - Wikimedia Commons File:Detailed view on chronograph pushers and crown (with open watch movement) of an Omega Cal. 1861 chronograph movement from an Omega Speedmaster (cropped).jpg - Wikimedia Commons](https://upload.wikimedia.org/wikipedia/commons/0/05/Detailed_view_on_chronograph_pushers_and_crown_%28with_open_watch_movement%29_of_an_Omega_Cal._1861_chronograph_movement_from_an_Omega_Speedmaster_%28cropped%29.jpg)
File:Detailed view on chronograph pushers and crown (with open watch movement) of an Omega Cal. 1861 chronograph movement from an Omega Speedmaster (cropped).jpg - Wikimedia Commons
![Introducing: The Omega Speedmaster Professional Moonwatch 'Master Chronometer' With Co-Axial Caliber 3861 - Hodinkee Introducing: The Omega Speedmaster Professional Moonwatch 'Master Chronometer' With Co-Axial Caliber 3861 - Hodinkee](https://hodinkee-production.s3.amazonaws.com/uploads/images/1609850389996-5f4dctmg6mr-d5e7cdf3b43f7ca0472d1d5d9a7dfe01/OMEGA310-30-42-50-01-002PUB.jpg)