Side by side

Bremont Supermarine 300MvsSeiko Prospex Marinemaster Marinemaster 1968 Heritage Diver's Watch

The numbers, the dial colors, the calibers — laid out so you can stop flipping between tabs.

Supermarine 300M
BremontSupermarine 300M
MSRP $3,550

At a glance

12 of 29 specs differ
Diameter
Supermarine 300M40mm
Prospex Marinemaster Marinemaster 1968 Heritage Diver's Watch42.6mm
Power Reserve
Supermarine 300M40h
Prospex Marinemaster Marinemaster 1968 Heritage Diver's Watch50h
Water Resistance
Supermarine 300M300m
Prospex Marinemaster Marinemaster 1968 Heritage Diver's Watch300m
MSRP
Supermarine 300M$3,550
Prospex Marinemaster Marinemaster 1968 Heritage Diver's Watch$2,900

Full specifications

Case

4 specs
Diameter
40mm
42.6mm
Thickness
12mm
13.4mm
Lug-to-Lug
49.3mm
Material
904L Stainless Steel
Stainless Steel

Crystal & Dial

4 specs
Crystal Shape
Flat
Curved
AR Coating
Inner
Anti-reflective coating on inner surface
Dial Color
Green
Black
Lume
None
LumiBrite on hands, index(es) and bezel

Movement

3 specs
Caliber
BE-92AE
8L35
Power Reserve
40h
50h
Jewels
25
26

Pricing

1 specs
MSRP
$3,550
$2,900

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What people say

Owners + reviewers, side by side

Synthesized for each watch independently from owner discussions, enthusiast forums, written reviews, and video reviewers.

Bremont Supermarine 300M

The Bremont Supermarine 300M is praised for its comfortable 40mm and 42mm case sizes, with owners noting the 42mm wears well on smaller wrists due to its lug design. One owner highlights the 13mm thinness of the 40mm case, considered compact for a 300m diver. The watch is priced at $1375. On balance, owners and reviewers appreciate the Bremont Supermarine 300M for its wearability and compact dimensions, especially for a dive watch.

Seiko Prospex Marinemaster Marinemaster 1968 Heritage Diver's Watch

The Seiko Prospex Marinemaster Marinemaster 1968 Heritage Diver's Watch is praised for its premium finishing, often described as Zaratsu-like, and robust build quality, with owners finding its 42mm case and 4 o'clock crown appealing for wearability. Some reviewers note its secondary GMT function and quieter bezel clicks may not suit all preferences, while one owner reported bezel misalignment issues. The watch is powered by the Caliber 8L45 automatic movement, offering a 72-hour power reserve and an accuracy rating of -5/+10 seconds per day, though some owners question its value proposition at its price point. On balance, owners and reviewers rate the Seiko Prospex Marinemaster Marinemaster 1968 Heritage Diver's Watch highly for its exceptional finishing and refined tool-like aesthetic.

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