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 Watch72h
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$3,600

Full specifications

Case

4 specs
Diameter
40mm
42.6mm
Thickness
12mm
14.1mm
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
8L45
Power Reserve
40h
72h
Jewels
25
35

Pricing

1 specs
MSRP
$3,550
$3,600

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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 1968 Heritage Diver's Watch is widely praised for its excellent quality and finishing, with reviewers and owners noting its GS-level craftsmanship and Zaratsu-inspired polishing. Owners appreciate its refined design, comfortable case shape, and the 4:00 crown position, with some finding it more manageable on the wrist than other models. The Caliber 8L45 movement offers a 72-hour power reserve and accuracy within -5/+10 seconds per day, and the bracelet features an improved clasp with an extension system. However, some find the price point high, and one reviewer noted the unsigned winding crown as a missed opportunity. On balance, owners and reviewers rate the Seiko Prospex Marinemaster 1968 Heritage Diver's Watch highly for its premium finishing and tool-like appearance at its price point.

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