Side by side

Marathon JDD (Jumbo Day/Date) Anthracite Diver's AutomaticvsFormex Reef 39.5 mm

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

JDD (Jumbo Day/Date) Anthracite Diver's Automatic
MarathonJDD (Jumbo Day/Date) Anthracite Diver's Automatic
MSRP $3,250
Reef 39.5 mm
FormexReef 39.5 mm
MSRP $2,230

At a glance

9 of 29 specs differ
Diameter
JDD (Jumbo Day/Date) Anthracite Diver's Automatic46mm
Reef 39.5 mm39.5mm
Power Reserve
JDD (Jumbo Day/Date) Anthracite Diver's Automatic40h
Reef 39.5 mm56h
Water Resistance
JDD (Jumbo Day/Date) Anthracite Diver's Automatic300m
Reef 39.5 mm300m
MSRP
JDD (Jumbo Day/Date) Anthracite Diver's Automatic$3,250
Reef 39.5 mm$2,230

Full specifications

Case

4 specs
Diameter
46mm
39.5mm
Thickness
18mm
11mm
Lug-to-Lug
55mm
45.5mm
Material
316L Stainless Steel (Anthracite IP)
Stainless Steel

Crystal & Dial

2 specs
Dial Color
Anthracite
Bahama Blue
Lume
None
Super-LumiNova

Movement

2 specs
Caliber
Sellita SW220-1
Sellita SW300-1
Power Reserve
40h
56h

Pricing

1 specs
MSRP
$3,250
$2,230

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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.

Marathon JDD (Jumbo Day/Date) Anthracite Diver's Automatic

Owners widely praise the Marathon JDD (Jumbo Day/Date) Anthracite Diver's Automatic as a tough, underrated tool watch with lifestyle appeal, highlighting its robust build and tritium lume for excellent legibility. However, its 46mm size is a common criticism, with some finding it heavy and top-heavy, and the OEM rubber strap stiff. One owner noted the watch runs about 10 seconds fast after three days, and the ETA 2836-2 movement offers approximately two days of power reserve. On balance, owners and reviewers rate the Marathon JDD (Jumbo Day/Date) Anthracite Diver's Automatic highly for its robust tool-watch build and legibility, despite its substantial size.

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.

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