Side by side

Formex Reef 39.5 mmvsSeiko Astron

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
Astron
SeikoAstron
MSRP $2,500

At a glance

15 of 29 specs differ
Diameter
Reef 39.5 mm39.5mm
Astron42mm
Power Reserve
Reef 39.5 mm56h
Astron40h
Water Resistance
Reef 39.5 mm300m
Astron100m
MSRP
Reef 39.5 mm$2,230
Astron$2,500

Full specifications

Case

7 specs
Category
Diver
GMT
Diameter
39.5mm
42mm
Thickness
11mm
12.4mm
Lug-to-Lug
45.5mm
49.5mm
Lug Width
22mm
14mm
Material
Stainless Steel
Titanium
Water Resistance
300m
100m

Crystal & Dial

3 specs
AR Coating
Inner
Super-clear coating
Dial Color
Bahama Blue
Black
Lume
Super-LumiNova
LumiBrite on hands and index(es)

Movement

4 specs
Caliber
Sellita SW300-1
5X83
Type
Automatic
Quartz
Power Reserve
56h
40h
Jewels
25
14

Pricing

1 specs
MSRP
$2,230
$2,500

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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 Astron

Owners widely praise the Seiko Astron for its spectacular technology, solar-powered quartz movement, and GPS time synchronization, making it a convenient grab-and-go option. The watch is frequently noted for its comfortable and lightweight titanium build, with some models featuring well-finished cases and robust ceramic bezels. Reviewers and owners alike highlight the dial's dynamic and shiny appearance, with textured hour markers and high-contrast edges. Accuracy is generally considered good, with figures ranging from +/- 15 seconds per month to within 1/2 second per day, easily corrected by GPS signal. However, some owners note that DST requires manual adjustment and that automatic time syncing depends on proximity to radio wave towers. The price point is a concern for some, who feel it competes with luxury watches without the same aesthetic appeal. One owner pointed out minimal lume and a slight misalignment of the minute hand on their model.

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