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Repair Windows errors before they cause bigger problemsFix Now →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →The Formex Reef GMT pairs a slim-for-its-rating 300 m stainless-steel case with a COSC-certified Sellita SW330-2 caller-style GMT movement and a bezel you can swap without tools. Its dimensions and customization make it an unusually versatile sports watch on paper; its modern, technical look and caller-GMT operation are the main considerations before buying.
Formex Reef GMT specifications at a glance
| Case | 316L stainless steel; 42 mm diameter, 47 mm lug-to-lug, 11.4 mm height (Formex also lists 9.4 mm perceived height), and 22 mm lug width. Formex lists case-only weight at 90 g. |
|---|---|
| Movement | Sellita SW330-2 automatic GMT; 25 jewels, date, quick-setting GMT hand, central 24-hour hand, 56-hour power reserve. Formex says each movement is COSC-certified. |
| Bezel | Bidirectional, 48-click, 24-hour scale; removable without tools. Formex offers ceramic and stainless-steel bezel options. |
| Crystal and back | Sapphire crystal with anti-reflective treatment; display case back. |
| Water resistance | Formex-rated 30 bar / 300 m / 1,000 ft. |
| Bracelet and strap options | Solid-link steel and mesh bracelets, plus leather and rubber straps; Formex describes quick-release fittings and micro-adjustment systems. |
These are Formex’s published specifications, not independently verified measurements. See the official black/red Reef GMT product page for the selected configuration and current listing.
How the caller-style GMT works
The Reef GMT uses a central 24-hour hand to show a second time zone. The local hour hand does not independently jump in the manner of a traveler-style GMT, so this is best understood as a caller GMT: set the extra hand to a reference time, then read it against the dial and the 24-hour scale. The date and GMT hand have quick-setting functions according to Formex; the cited hands-on review identifies the movement as caller-style.
To follow a third time zone, rotate the bidirectional bezel so its 24-hour markings shift relative to the GMT hand. The 48-click mechanism allows the bezel to be positioned around the dial, with the GMT hand and bezel together providing another offset reading. It is a useful arrangement for someone who wants home or reference time plus another time zone, but travelers who prioritize changing local time by jumping the main hour hand may prefer a different GMT movement.
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#1 Best Overall
- DURABLE PERFORMANCE – Our most innovative dive-style watch is tested to 100 meters of water resistance and tracks multiple time zones. The Fossil Blue GMT also features a rotating 24-hr bezel, bold oversized crown, and lume indices for easy readability. Made for any adventure. *Not ISO-certified.
- ALL-DAY DURABILITY: 46mm case, 24mm band width, hardened mineral crystal lens resists scratches, GMT movement with GMT analog display echoing craftsmanship of fine watches, men's watch, imported.
- LARGE DIAL STYLE: Round silver and blue stainless steel case with a blue sunray dial and white accents, an ideal analog watch design inspired by classic big face watches.
- DURABLE STEEL BAND: Silver stainless steel bracelet for men's watch and big face watches, secure fold-over clasp; removable links for customized fit; interchangeable with all 24mm Fossil straps.
- ALL-DAY WATER DEFENSE – Water Resistant up to 100m (330ft): suitable for bathing, swimming or snorkeling, but is not resistant enough to withstand scuba diving; 10 ATM, ideal for those who rotate watches
Fit and everyday wear
At 42 mm across, the Reef GMT is not a small watch, but the 47 mm lug-to-lug and 11.4 mm stated height give useful context beyond diameter alone. Formex lists 9.4 mm as its perceived height; that is the manufacturer’s characterization, not a separate measured case thickness. The 22 mm lug width also means the watch has a substantial strap footprint.
Thomas Van Straaten, writing for Fratello after wearing the watch in daily life, described the 42 mm model as large but comfortable on his 17 cm wrist. He credited the relatively short lug-to-lug measurement and slim profile with helping it wear well. He also praised the bracelet’s solidity, while wishing it tapered more aggressively. Those are one reviewer’s observations, not a guarantee of fit on every wrist.
Rank #2
- Technomarine Reef Chronograph GMT Quartz Unisex Watch TM-523004
Bezel and strap customization
The bezel is the Reef GMT’s standout practical distinction. Formex says it can be removed without tools and that GMT bezels are interchangeable with bezels from the Reef diver line. On the GMT, the compatible diver bezels operate bidirectionally, according to Van Straaten’s review. Formex offers ceramic bezels and a stainless-steel option; check that a replacement is listed for the exact Reef configuration before ordering.
Formex also offers steel-link and mesh bracelets, leather straps, and rubber straps with quick-release fittings, alongside micro-adjustment systems. These make changing the watch’s look or fit simpler than a conventional fixed bracelet setup, though compatibility and availability should be confirmed for the specific piece and accessory.
Rank #3
- Automatic GMT Movement: Seiko NH34
- Case & Bracelet Material: 316L Stainless Steel
- Water Resistance: Up to 200M
- Crystal: Sapphire with Anti-Reflective Coating
- Hour Markers: Applied Indexes
300 m water resistance is not the same as a dive-watch certification
Formex specifies 30 bar, equivalent to 300 m or 1,000 ft, of water resistance. That rating is a manufacturer specification. Fratello notes that Formex does not position the Reef GMT as a diver, and the available information does not establish ISO diver-watch certification. Buyers should therefore treat it as a highly water-resistant sports GMT, not assume it has been certified to a diver-watch standard.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Design and finishing: a technical sports-watch character
Van Straaten characterized the Reef GMT as sporty, modern, and technical rather than formal. He found its finishing acceptable for its price range but wanted sharper transitions and edges, as well as deeper brushing. He liked the feature set and concept more than the design itself. If you want a watch that easily moves from casual wear to dressier settings, his review suggests the Reef GMT’s visual language may be a limitation; that remains a matter of taste.
Rank #4
- GMT FUNCTION: Features a 24-hour bezel and GMT hand for tracking multiple time zones with precision and ease
- PREMIUM CONSTRUCTION: Dome sapphire crystal face provides superior scratch resistance while stainless steel case ensures durability
- AUTOMATIC MOVEMENT: Powered by reliable NH34 automatic mechanical movement, eliminating the need for batteries
- LUMINOUS DISPLAY: Bright blue lume on hands and markers enables excellent nighttime visibility
- WATER RESISTANT: 100m/330ft water resistance rating makes it suitable for swimming and snorkeling
Price and buying context
When accessed on October 8, 2026, Formex’s official page listed the black/red 42 mm configuration at CHF 1,920. Prices can change, and that Swiss-franc listing should not be treated as a like-for-like quote for another market or configuration. Fratello reported a starting price of €1,770 / US$1,835 including VAT and shipping on September 24, 2022; that is historical pricing, not a current offer.
The purchase case is strongest if you value the combination of COSC certification as stated by Formex, 300 m published water resistance, the 56-hour reserve, and an unusually adaptable bezel-and-strap system. Consider another option if you specifically need a traveler GMT with an independently jumping local hour hand, a more understated design, or a confirmed diver-watch certification.
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Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
