Side by side

Formex Reef 39.5 mmvsSeiko Prospex Marinemaster Marinemaster 1965 Heritage Diver's Watch

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

Reef 39.5 mm
FormexReef 39.5 mm
MSRP $2,230

At a glance

12 of 29 specs differ
Diameter
Reef 39.5 mm39.5mm
Prospex Marinemaster Marinemaster 1965 Heritage Diver's Watch39.5mm
Power Reserve
Reef 39.5 mm56h
Prospex Marinemaster Marinemaster 1965 Heritage Diver's Watch45h
Water Resistance
Reef 39.5 mm300m
Prospex Marinemaster Marinemaster 1965 Heritage Diver's Watch200m
MSRP
Reef 39.5 mm$2,230
Prospex Marinemaster Marinemaster 1965 Heritage Diver's Watch$2,800

Full specifications

Case

4 specs
Thickness
11mm
12.3mm
Lug-to-Lug
45.5mm
47.2mm
Lug Width
22mm
20mm
Water Resistance
300m
200m

Crystal & Dial

4 specs
Crystal Shape
Flat
Box
AR Coating
Inner
Anti-reflective coating on inner surface
Dial Color
Bahama Blue
Black
Lume
Super-LumiNova
LumiBrite on hands, index(es) and bezel

Movement

3 specs
Caliber
Sellita SW300-1
6L37
Power Reserve
56h
45h
Jewels
25
26

Pricing

1 specs
MSRP
$2,230
$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.

Formex Reef 39.5 mm

The Formex Reef 39.5 mm is widely praised for its refined finishing, comfortable and well-proportioned case design, and impressive specifications for its price point, including COSC-certified Sellita SW300-1 movement and 300m water resistance. Owners and reviewers highlight the tool-less micro-adjust clasp and quick-release spring bars as practical features. Some reviewers note that the 22mm lug width feels slightly disproportionate to the smaller case, and the bracelet could benefit from more taper, though this is a point of contention for some owners who value the overall package. A prototype crown protrusion issue is noted as being addressed for production. On balance, owners and reviewers rate the Formex Reef 39.5 mm highly for its excellent value and well-executed design.

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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