1985 Omega Speedmaster Automatic (Ref. 176.0012) "Mark 4.5"

With the immense success Omega saw from the Speedmaster Professional series, especially after its iconic trip to the moon, they decided the expand the Speedmaster model with the ever-evolving Mark series of chronographs. The Mark II debuted in 1969 with a bold, sunburst-finished tonneau-style case. The Mark III was introduced in 1971 and was the first Speedmaster to employ an automatic winding movement using the Lemania cal. 1340. The Mark IV was introduced in 1973 and melded the Mark II case style with the same Lemania-based movement of the Mark III. After a short hiatus, Omega created the Mark V which featured a very evolved aesthetic that many refer to as 'futuristic'.

So what is a Speedmaster Mark 4.5? The ref. 176.0012, also known as the"Mark 4.5", is the unofficial name of the Speedmaster Automatic that bridges the gap between the Mark IV and the Mark V. This model employs a very similar case to the Mark IV but employs the same movement as the Mark V, the Lemania cal. 5100. Interestingly the Mark 4.5 was manufactured for the longest period out of the actual models in the Mark Series, from 1974 to 1986. 

Stock # OSPMMK45
Brand Omega
Style Speedmaster Automatic "Mark 4.5"
Model 176.00012
Serial 45XXXXXX
Size Men's
Material Stainless Steel 
Dial Matte Black
Millimeters 42x45
Bracelet Omega 1162 Bracelet W/ 172 End Pieces


The robust and large tonneau-style case is in wonderful condition with the impressive sunburst finish still intact and the broad bevel fully present as well, though the case does appear to have been gently polished in the past and shows light wear from use. The case retains its original pump pushers and Omega-signed crown. The original mineral glass crystal has some minor scratches and wear but they are very subtle and don't detract from the aesthetic of the watch. The case back remains very crisp with the Seamaster medallion remaining fully intact. The original Omega 1162/172 stainless steel bracelet retains 20 links that show expected stretch for the style and age of the bracelet and will fit up to a 7 1/2-inch wrist. 


The original matte black dial is flawless, showing no age or damage whatsoever. The tritium lume plots feature a pale ivory color with no degradation present under UV light inspection. The original tritium hands have taken on a grey patina which is common for these models, and no degradation is present under UV light inspection.


None. The watch is keeping time, but the service history is unknown. A movement service can be provided upon request.