Formex Reef 39.5 mmvsSeiko Prospex Marinemaster 1965 Heritage Diver's Watch

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Measurements

Catalog photos are all shot at the same flattering size. These aren't: every case below shares one millimeter scale.

Formex Reef 39.5 mm at true scale

Reef 39.5 mm

Seiko Prospex Marinemaster 1965 Heritage Diver's Watch at true scale

Prospex Marinemaster 1965 Heritage Diver's Watch

Diameter

39.5mm

39.5mm

Lug-to-Lug

45.5mm

lowest

47.2mm

Thickness

11mm

lowest

12.3mm

Water Resistance

300m

highest

200m

Power Reserve

56h

highest

45h

MSRP

$2,230

lowest

$2,800

Movement

Sellita SW300-1

Seiko 6L37

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
n/a
Box
AR Coating
n/a
Anti-reflective coating on inner surface
Dial Color
Bahama Blue
n/a
Lume
Super-LumiNova
LumiBrite on hands, index(es) and bezel

Movement

3 specs
Caliber
Sellita SW300-1
Seiko 6L37
Power Reserve
56h
45h
Jewels
0
26

Pricing

1 specs
MSRP
$2,230
$2,800
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Reviews

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, improved proportions, and compelling value under €2,000. Owners and reviewers highlight its comfortable wearability on smaller wrists, unique aesthetic, and impressive specifications including 300m water resistance and a COSC-certified Sellita SW300-1 movement. Some note the 22mm lug width feels slightly disproportionate and the bracelet could benefit from more taper. A prototype crown protrusion issue is expected to be resolved in production. Overall, owners rate the Formex Reef 39.5 mm highly for its excellent build quality and tool-like features at its price point.

Seiko Prospex Marinemaster 1965 Heritage Diver's Watch

The Seiko Prospex Marinemaster Marinemaster 1965 Heritage Diver's Watch is praised for its modern execution of a classic design, with reviewers noting the appealing 39.5mm case size and updated bracelet that improve wearability. Some reviewers mention the 6L37 movement has a 46-hour power reserve, with accuracy rated around -10/+15 seconds per day. A drawback identified by reviewers is the lack of tool-free micro-adjustment on the clasp. Overall, owners and reviewers find the Seiko Prospex Marinemaster Marinemaster 1965 Heritage Diver's Watch to be a handsome re-interpretation of a beloved design, with its improved wearability being a key strength.

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