Side by side

Bremont Supermarine 300MvsSeiko Prospex Marinemaster Marinemaster 1965 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

13 of 29 specs differ
Diameter
Supermarine 300M40mm
Prospex Marinemaster Marinemaster 1965 Heritage Diver's Watch39.5mm
Power Reserve
Supermarine 300M40h
Prospex Marinemaster Marinemaster 1965 Heritage Diver's Watch45h
Water Resistance
Supermarine 300M300m
Prospex Marinemaster Marinemaster 1965 Heritage Diver's Watch200m
MSRP
Supermarine 300M$3,550
Prospex Marinemaster Marinemaster 1965 Heritage Diver's Watch$2,800

Full specifications

Case

5 specs
Diameter
40mm
39.5mm
Thickness
12mm
12.3mm
Lug-to-Lug
47.2mm
Material
904L Stainless Steel
Stainless Steel
Water Resistance
300m
200m

Crystal & Dial

4 specs
Crystal Shape
Flat
Box
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
6L37
Power Reserve
40h
45h
Jewels
25
26

Pricing

1 specs
MSRP
$3,550
$2,800

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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 1965 Heritage Diver's Watch

The Seiko Prospex Marinemaster 1965 Heritage Diver's Watch is praised for its faithful re-creation of the 62MAS design, with reviewers noting improved wearability due to smaller case sizes (38mm to 40mm) and updated bracelets. Specific models feature a stainless steel case with super-hard coating, ceramic bezel, and a tool-free extension system on the bracelet. Accuracy figures vary, with one model rated at -5/+10 seconds per day and another at -10/+15 seconds per day, powered by movements like the Caliber 8L45 or 6L37 offering 72-hour or 46-hour power reserves respectively. Some reviewers point out drawbacks such as an unsigned winding crown, a lack of tool-free micro-adjust on the clasp for certain models, and a secondary GMT function on one variant. The price point, ranging from $2,800 to $3,600, is considered high by some, especially when compared to other Seiko or Grand Seiko offerings.

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