Side by side

Formex Reef 39.5 mmvsSeiko Prospex Sea Seiko Diver’s Watch 60th Anniversary Limited Edition

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

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 Diver’s Watch 60th Anniversary Limited Edition

The Prospex Sea Seiko Diver’s Watch 60th Anniversary Limited Edition features a 40mm case, 300m water resistance, and a 72-hour power reserve from the Calibre 6R55 movement, distinguished by a grey bezel insert and a wave-patterned silvery-white dial. The clasp includes an improved diving suit extension. Owners note the MarineMaster case is comfortable and wearable. However, some owners criticize the 6R54 movement's accuracy, reporting deviations of +25/-15 seconds per day, and find the production number too large for a "limited" edition, deeming it too expensive. On balance, owners rate the Prospex Sea Seiko Diver’s Watch 60th Anniversary Limited Edition positively for its comfortable case and attractive dial, despite concerns regarding its price and movement accuracy.

At a glance

12 of 29 specs differ
Diameter
Reef 39.5 mm39.5mm
Prospex Sea Seiko Diver’s Watch 60th Anniversary Limited Edition40mm
Power Reserve
Reef 39.5 mm56h
Prospex Sea Seiko Diver’s Watch 60th Anniversary Limited Edition72h
Water Resistance
Reef 39.5 mm300m
Prospex Sea Seiko Diver’s Watch 60th Anniversary Limited Edition300m
MSRP
Reef 39.5 mm$2,230
Prospex Sea Seiko Diver’s Watch 60th Anniversary Limited Edition$1,400

Full specifications

Case

4 specs
Diameter
39.5mm
40mm
Thickness
11mm
13mm
Lug-to-Lug
45.5mm
46.4mm
Lug Width
22mm
20mm

Crystal & Dial

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

Movement

3 specs
Caliber
Sellita SW300-1
6R55
Power Reserve
56h
72h
Jewels
0
24

Pricing

1 specs
MSRP
$2,230
$1,400
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