Side by side

Formex Reef GMTvsSeiko 5 Sports Field series

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

Reef GMT
FormexReef GMT
MSRP $2,235
5 Sports Field series
Seiko5 Sports Field series
MSRP $450

At a glance

12 of 29 specs differ
Diameter
Reef GMT42mm
5 Sports Field series39.4mm
Power Reserve
Reef GMT56h
5 Sports Field series41h
Water Resistance
Reef GMT300m
5 Sports Field series100m
MSRP
Reef GMT$2,235
5 Sports Field series$450

Full specifications

Case

5 specs
Diameter
42mm
39.4mm
Thickness
11.4mm
13.6mm
Lug-to-Lug
47mm
47.9mm
Lug Width
22mm
20mm
Water Resistance
300m
100m

Crystal & Dial

3 specs
Crystal
Sapphire
Hardlex
Crystal Shape
Flat
Curved
Lume
Super-LumiNova
LumiBrite on hands and index(es)

Movement

3 specs
Caliber
Sellita SW330-2
4R34
Power Reserve
56h
41h
Jewels
25
24

Pricing

1 specs
MSRP
$2,235
$450

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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 GMT

The Formex Reef GMT is widely praised for its unique porthole case shape, COSC-certified Sellita SW330-2 movement with good finishing, and comfortable quick-release bracelet with on-the-fly micro-adjustment. Reviewers note its robust construction, impressive specifications, and strong value proposition, with a slim 11.4mm profile accommodating 300m water resistance and an exhibition caseback. However, owners widely report the 53mm lug-to-lug span with male endlinks makes it too large for smaller wrists. Some find the bezel action stiff and potentially slippery, and a reviewer desired sharper finishing and edges, deeming the aesthetic too modernist. The GMT variant sacrifices a timing bezel unless swapped, and one owner notes sharp edges on the crown and crown guard. Overall, owners and reviewers highly rate the Formex Reef GMT for its exceptional value and well-executed features, particularly its bracelet system and COSC-certified movement.

From video reviewers

The watch features a COSC-certified SW330-2 GMT movement, which is visible through a sapphire crystal display case back and beautifully decorated. The watch's water-resistance of up to 300m/1000ft is a notable feature. The 42mm diameter may be too large for smaller wrists.

Seiko 5 Sports Field series

The Seiko 5 Sports Field series offers an accessible explorer-style watch with a 41mm stainless steel case, 100m water resistance, and a Hardlex crystal. The Field GMT model features a caller GMT complication powered by the 4R34 movement, while the standard Field models use the 4R36 with a 41-hour power reserve. Both models include Arabic numerals coated in LumiBrite and a lumed pearl on the bezel. On balance, the Seiko 5 Sports Field GMT is a well-regarded entry-level explorer watch for its price point, despite its office-style GMT function.

From video reviewers

The prominent five-sided GMT hand enhances legibility and adds a sophisticated aesthetic to the watch. The Seiko 5 Sports Field series offers similar functionality to the Explorer 2 at a lower price, making it a valuable option. Reviewers disagree on whether it's a missed opportunity for Seiko to release this model first, with one reviewer implying it would have been a more logical addition to their lineup.

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