Side by side

Fortis Marinemaster M-40vsSeiko King Seiko KSK

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

Marinemaster M-40
FortisMarinemaster M-40
MSRP $3,520
King Seiko KSK
SeikoKing Seiko KSK
MSRP $1,900

At a glance

14 of 29 specs differ
Diameter
Marinemaster M-4040mm
King Seiko KSK36.1mm
Power Reserve
Marinemaster M-4038h
King Seiko KSK72h
Water Resistance
Marinemaster M-40300m
King Seiko KSK100m
MSRP
Marinemaster M-40$3,520
King Seiko KSK$1,900

Full specifications

Case

6 specs
Category
Diver
Dress
Diameter
40mm
36.1mm
Thickness
13mm
11.6mm
Lug-to-Lug
43mm
Lug Width
21mm
19mm
Water Resistance
300m
100m

Crystal & Dial

4 specs
Crystal Shape
Flat
Box
AR Coating
Inner
Anti-reflective coating on inner surface
Dial Color
Orange
Black
Lume
None
LumiBrite on hands and index(es)

Movement

3 specs
Caliber
Sellita SW220-1
6R51
Power Reserve
38h
72h
Jewels
26
24

Pricing

1 specs
MSRP
$3,520
$1,900

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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.

Fortis Marinemaster M-40

Owners praise the Fortis Amber Orange for its gorgeous appearance and strong wrist presence, noting its crazy lume and 70-hour power reserve. The Doxa SUB 300T, described as having a superb, eccentric design with a highly legible dial and functional no-decompression bezel, uses an ETA 2824-2 movement. However, the SUB 300T's 42.5mm case wears large and its 14mm thickness is not ideal for dress shirts, though it boasts 1,200m water resistance. On balance, owners appreciate the Fortis Amber Orange for its striking aesthetics and impressive lume.

Seiko King Seiko KSK

The King Seiko KSK is widely praised for its refined finishing, with owners and reviewers noting its sharp case, faceted lugs, and well-executed dial indices, often comparing its polishing favorably to Grand Seiko. Enthusiasts appreciate its slim, retro design, with some stating it wears smaller than its official size due to the cushion case and close-to-the-wrist feel. The use of the slimline Calibre 6L35 movement is seen as an upgrade, maintaining the watch's slender profile, though some owners express concern over the price point and the perceived value of the movement. Accuracy figures vary, with one owner reporting +5 to +7 seconds per day, while another notes +15/-10 seconds per day. Some owners have noted minor quality control issues such as misaligned screws or a burr on a hand. On balance, owners and reviewers rate the King Seiko KSK highly for its exceptional case and dial finishing at its price point.

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