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 $900
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

Owners widely praise the Seiko Prospex Sea for its excellent lume, robust build, and value, with many highlighting the comfortable 4 o'clock crown and reliable movements. Reviewers note impressive case finishing and attractive dials, with specific models lauded for their gradient blue designs and smooth bezel actions. Accuracy figures vary, with one owner reporting +9 seconds/day after demagnetization, while others find the watches to be good first "proper" watches. Some owners find the stock rubber straps uncomfortable or the overall size substantial on smaller wrists. On balance, owners and reviewers rate the Seiko Prospex Sea highly for its combination of strong dive watch functionality and appealing design at its price point.

At a glance

13 of 29 specs differ
Diameter
Reef 39.5 mm39.5mm
Prospex Sea41mm
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$900

Full specifications

Case

5 specs
Diameter
39.5mm
41mm
Thickness
11mm
12.3mm
Lug-to-Lug
45.5mm
46.9mm
Lug Width
22mm
20mm
Water Resistance
300m
200m

Crystal & Dial

4 specs
Crystal Shape
Flat
Curved
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
6R35
Power Reserve
56h
70h
Jewels
25
24

Pricing

1 specs
MSRP
$2,230
$900
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