Bremont Supermarine 300MvsSynchron Poseidon

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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.

Supermarine 300M

Poseidon
Diameter
40mm
41mm
Lug-to-Lug
n/a
45mm
Thickness
12mm
11.9mm
lowest
Water Resistance
300m
300m
Power Reserve
n/a
68h
MSRP
$3,550
n/a
Movement
Bremont BE-92AE
La Joux-Perret G100
Case
4 specsCrystal & Dial
1 specsMovement
2 specsPricing
1 specsReviews
Synthesized for each watch independently from owner discussions, enthusiast forums, written reviews, and video reviewers.
The Bremont Supermarine 300M is praised for its comfortable 40mm case, which some owners find wears well even on smaller wrists due to its lug design, outperforming some 40mm watches. One forum contributor notes the 40mm case is relatively compact for a 300m diver and is priced at $1375. A reviewer found the 40mm case comfortable. On balance, owners and reviewers appreciate the Bremont Supermarine 300M's wearable 40mm case size and comfortable wearability.
Owners widely praise the Synchron Poseidon for its vintage-inspired diver aesthetics, easy-to-read dial, and precise, grippy bezel. The La Joux-Perret G100 movement is consistently noted as a strong point, with owners reporting good timekeeping, one seeing accuracy around -4 seconds per day, and others highlighting its 68-hour power reserve. The winding action and crown operation are described as reassuring, with one reviewer stating it surpasses watches at double the price. Some find the design busy or the branding confusing, and the blasted finish on the steel bezel rim contrasts with the brushed case. One owner noted the included Isofrane strap can be long for smaller wrists. On balance, owners and reviewers rate the Synchron Poseidon highly for its robust build, reliable movement, and excellent value.
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