Side by side

Formex Reef 39.5 mmvsSeiko Prospex Sea

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
Prospex Sea
SeikoProspex Sea
MSRP $1,500

At a glance

12 of 29 specs differ
Diameter
Reef 39.5 mm39.5mm
Prospex Sea43.5mm
Power Reserve
Reef 39.5 mm56h
Prospex Sea70h
Water Resistance
Reef 39.5 mm300m
Prospex Sea200m
MSRP
Reef 39.5 mm$2,230
Prospex Sea$1,500

Full specifications

Case

5 specs
Diameter
39.5mm
43.5mm
Thickness
11mm
13.3mm
Lug-to-Lug
45.5mm
51mm
Material
Stainless Steel
Titanium
Water Resistance
300m
200m

Crystal & Dial

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

Movement

3 specs
Caliber
Sellita SW300-1
6R35
Power Reserve
56h
70h
Jewels
25
24

Pricing

1 specs
MSRP
$2,230
$1,500

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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 Prospex Sea

Seiko Prospex Sea owners and reviewers praise its Marinemaster-style aesthetic, excellent case finishing, and impressive LumiBrite lume. The watch is powered by the 6R15 movement with a 50-hour power reserve and comes with both a steel bracelet and a silicone strap. Some owners find the Seiko Prospex Sea to be a great value and a suitable first "proper" watch, while others report it is uncomfortably big, thick, and heavy on smaller wrists. Reviewers note the GMT function is secondary with a less prominent scale, and the bezel's quieter clicks may not appeal to all. On balance, owners and reviewers rate the Seiko Prospex Sea highly for its classic design and finishing at its price point.

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