Side by side

Formex Reef 39.5 mmvsSeiko Prospex Sea 1968 Heritage Diver's GMT Watch Limited Edition

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

11 of 29 specs differ
Diameter
Reef 39.5 mm39.5mm
Prospex Sea 1968 Heritage Diver's GMT Watch Limited Edition42mm
Power Reserve
Reef 39.5 mm56h
Prospex Sea 1968 Heritage Diver's GMT Watch Limited Edition72h
Water Resistance
Reef 39.5 mm300m
Prospex Sea 1968 Heritage Diver's GMT Watch Limited Edition300m
MSRP
Reef 39.5 mm$2,230
Prospex Sea 1968 Heritage Diver's GMT Watch Limited Edition$1,750

Full specifications

Case

4 specs
Diameter
39.5mm
42mm
Thickness
11mm
13.3mm
Lug-to-Lug
45.5mm
48.6mm
Lug Width
22mm
20mm

Crystal & Dial

3 specs
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
6R54
Power Reserve
56h
72h
Jewels
25
24

Pricing

1 specs
MSRP
$2,230
$1,750

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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 Sea 1968 Heritage Diver's GMT Watch Limited Edition

The Seiko Prospex Sea 1968 Heritage Diver's GMT Watch Limited Edition is widely praised for its excellent quality and finishing relative to its price point, featuring a beautiful case, bracelet, and strong Lumibrite lume. Enthusiasts and reviewers highlight the comfortable 42mm case size and the distinctive 4 o'clock crown position. The watch is powered by the in-house 6R54 automatic movement, offering a 72-hour power reserve and rated accuracy of -5/+10 seconds per day, though one source notes the GMT function is secondary. Some find the 4:30 date window divisive, and the bezel clicks are described as quieter than expected. On balance, owners and reviewers rate the Seiko Prospex Sea 1968 Heritage Diver's GMT Watch Limited Edition highly for its refined design and strong value proposition.

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