Omega Seamaster Diver 300M Co Axial Master Chronometer Chronograph 44mmvsOmega Speedmaster Moonphase Co Axial Master Chronometer Moonphase Chronograph 44 25mm

Ref. 210.60.44.51.03.001·MSRP $27,300

Ref. 304.63.44.52.01.001·MSRP $42,400
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Measurements
Catalog photos are all shot at the same flattering size. These aren't: every case below shares one millimeter scale.

Seamaster Diver 300M Co Axial Master Chronometer Chronograph 44mm

Speedmaster Moonphase Co Axial Master Chronometer Moonphase Chronograph 44 25mm
Diameter
44mm
44.3mm
Lug-to-Lug
52.8mm
50mm
lowest
Thickness
17.2mm
16.9mm
lowest
Water Resistance
300m
highest
100m
Power Reserve
60h
60h
MSRP
$27,300
lowest
$42,400
Movement
Omega 9900
Omega 9904
Case
5 specsMovement
2 specsPricing
1 specsReviews
Synthesized for each watch independently from owner discussions, enthusiast forums, written reviews, and video reviewers.
Owners widely report the Omega Seamaster Diver 300M Co Axial Master Chronometer Chronograph 44mm offers adequate wrist presence and can handle an active lifestyle, with one owner cherishing it as a daily watch. Some reviewers and owners find the 44mm case size could be more proportional and comfortable, with a preference expressed for a 40-42mm option, and one owner noted the bracelet felt "chunky." The helium escape valve is considered an esoteric feature for most users. Overall, owners and reviewers rate the Omega Seamaster Diver 300M Co Axial Master Chronometer Chronograph 44mm highly for its durability and suitability as an everyday watch, despite some reservations about its size.
The Omega Speedmaster Moonphase Co Axial Master Chronometer Moonphase Chronograph 44 25mm is widely praised for its detailed and photorealistic moonphase complication, featuring a boot print Easter egg, and its exceptional finishing, including a ceramic bezel and sun-brushed dial. Owners and reviewers consistently highlight the beauty of the complication and the overall build quality. However, the watch's 44.25mm case size and considerable thickness (around 16.85mm to 17mm) are frequently noted as making it wear large and potentially challenging to fit under dress cuffs, with some suggesting it feels "chunky" or like a "beast." One reviewer found the crown guards sharp when winding and the crown difficult to pull out. On balance, owners and reviewers appreciate the Omega Speedmaster Moonphase Co Axial Master Chronometer Moonphase Chronograph 44 25mm for its stunning moonphase detail and high-end finishing, despite its substantial size.
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