Side by side

Formex Reef 39.5 mmvsSeiko Prospex Marinemaster Marinemaster 1965 Diver’s Modern Re-interpretation

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

12 of 29 specs differ
Diameter
Reef 39.5 mm39.5mm
Prospex Marinemaster Marinemaster 1965 Diver’s Modern Re-interpretation39.5mm
Power Reserve
Reef 39.5 mm56h
Prospex Marinemaster Marinemaster 1965 Diver’s Modern Re-interpretation45h
Water Resistance
Reef 39.5 mm300m
Prospex Marinemaster Marinemaster 1965 Diver’s Modern Re-interpretation200m
MSRP
Reef 39.5 mm$2,230
Prospex Marinemaster Marinemaster 1965 Diver’s Modern Re-interpretation$2,800

Full specifications

Case

4 specs
Thickness
11mm
12.3mm
Lug-to-Lug
45.5mm
47.2mm
Lug Width
22mm
20mm
Water Resistance
300m
200m

Crystal & Dial

4 specs
Crystal Shape
Flat
Box
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
6L37
Power Reserve
56h
45h
Jewels
25
26

Pricing

1 specs
MSRP
$2,230
$2,800

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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 Marinemaster Marinemaster 1965 Diver’s Modern Re-interpretation

The Seiko Prospex Marinemaster Marinemaster 1965 Diver’s Modern Re-interpretation is noted for its refined, slimmed-down 39.5mm stainless steel case with a "super hard" coating and a box-shaped sapphire crystal. It offers 200 meters of water resistance and is powered by the slim Caliber 6L37 automatic movement, which has a 46-hour power reserve and an accuracy rating of -10/+15 seconds per day. Reviewers highlight its wearability and functionality as a dive watch, with one noting it as Seiko's thinnest diver ever at 12.3mm. However, concerns are raised about Seiko's continued reliance on the 62MAS design, with one reviewer wishing the Marinemaster remained a separate line, and the bracelet's end-links appearing mismatched in initial images. Its price of A$4,650 is considered high given its specifications compared to competitors.

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