Formex Reef 39.5 mmvsSeiko Prospex Sea 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 Sea 1965 Heritage Diver's Watch at true scale

Prospex Sea 1965 Heritage Diver's Watch

Diameter

39.5mm

40mm

Lug-to-Lug

45.5mm

lowest

46.4mm

Thickness

11mm

lowest

13mm

Water Resistance

300m

300m

Power Reserve

56h

72h

highest

MSRP

$2,230

$1,300

lowest

Movement

Sellita SW300-1

Seiko 6R55

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
n/a
Curved
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 6R55
Power Reserve
56h
72h
Jewels
0
24

Pricing

1 specs
MSRP
$2,230
$1,300
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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 Sea 1965 Heritage Diver's Watch

Owners widely praise the Seiko Prospex Sea 1965 Heritage Diver's Watch for its refined engineering, comfortable 40mm case, and improved 300m water resistance. The watch is noted for its better build quality and finishing compared to some alternatives, featuring a mix of polished and brushed surfaces, with specific callouts for the jewel-toned teal dial with a rippling-water pattern. Some owners consider the price fair, while others suggest it is too high. Accuracy figures vary, with some owners reporting their 6R55 movement performs well within +/- 10 seconds per day, while others note theirs runs slow or have concerns about QC for the price. The bracelet, while improved, lacks modern features like quick-release or extensive micro-adjustments. Overall, owners and reviewers rate the Seiko Prospex Sea 1965 Heritage Diver's Watch highly for its refined design and build quality at its price point.

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