Omega Speedmaster Professional (transitional caliber 321) vs Omega Speedmaster Professional

Side-by-side at a glance. Click a watch above to open the full reference page.

	Omega 145.012	Omega 310.30.42.50.01.002
Model	Speedmaster Professional (transitional caliber 321)	Speedmaster Professional
Caliber	Lemania Cal. 321 -- manual-wind column-wheel chronograph, 18,000bph, 48h PR; lateral clutch, triple-hammer; same caliber used on Moonwatch NASA mission	Omega Cal. 3861 -- Co-Axial Master Chronometer, manual-wind, 21,600bph, 50h PR, 33j; column-wheel, METAS-certified, anti-magnetic to 15,000 gauss
Case size	42mm	42mm
Lug-to-lug	46.2mm	46.2mm
Years produced	1967–1968	2021–present
Brand tier	luxury	luxury
Era	vintage	modern
Movement tier	Unclassified movement	In-house manufacture
Market median (excellent / full-set)	n/a	n/a
Typical range	n/a	n/a
Confidence	low	low
Categories	chronograph, sport	chronograph, sport
Editorial	yes	yes
Typical price (2026)	$18,000 – $28,000	$5,500 – $7,500
Service	n/a	Every 8 years · $600 – $900
Collector note	most sought: Pre-Moon reference with Cal 321; the most collectible Speedmaster outside the earliest refs.	landmark: The Cal. 3861 Moonwatch is the only watch NASA has ever certified for extra-vehicular activity and remains in continuous production, making it the single most historically documented wristwatch in circulation.
Named dial variants	1 variant	1 variant