Fleuss GMT SP-5120-99 a burnt orange travel diver with two straps

What is new about the Fleuss GMT SP-5120-99?

Spinnaker is a dive-inspired brand that sells mostly through its own shops, and the Fleuss is named after Henry Fleuss, whom the brand credits with inventing self-contained underwater breathing apparatus in 1878. The three-hand Fleuss has been around for some time. The GMT version is the newer idea. Worn & Wound ran Spinnaker's launch feature for it on 7 June 2024, describing it as the latest addition to a GMT family that already included the Dumas, Croft and Bradner.

The SP-5120-99 is the Burnt Orange model. Spinnaker's UK shop lists it among the new colours that joined the line in June 2024, alongside a Midnight Wave blue and a Sandstorm Brown. It pairs a graded orange dial with a two-tone 24-hour bezel, blue for the night hours and red for the day. Spinnaker's own spec table calls the dial red, so expect it to read as a warm red-orange rather than a pale tangerine.

The bigger draw is what comes in the box. Spinnaker supplies a solid steel beads of rice bracelet and a second, red rubber strap, so the same watch can be dressed up or taken to the pool.

How big is it, and how will it wear?

Spinnaker quotes a 43 mm case, 13 mm thick, with a 51 mm lug to lug and 22 mm lugs. Those are full-size dive watch numbers. On a wrist of about 7 inches it should sit right at the edge of the lugs, and Spinnaker's own sizing guide suggests 42 to 44 mm for medium to large wrists. If your wrist is nearer 6 inches, it will overhang.

The brand gives a weight of 190 grams on the bracelet, which is noticeable. Swapping to the rubber strap will take a good share of that off and make the watch feel less top-heavy. The 13 mm height is reasonable for an automatic GMT and should slide under most cuffs.

What movement does it use, and how accurate is it?

Inside is the NH34, an automatic GMT calibre made by Seiko's movement arm (Spinnaker lists it as TMI NH34, Long Island Watch as Seiko NH34). Spinnaker gives the basics: 24 jewels, 21,600 beats per hour, a date and a second time zone. The extra hand runs on a 24-hour scale, and with the rotating bezel you can track a third zone as well.

The NH34 is a so-called office or caller GMT: you set the 24-hour hand on its own with the crown, rather than jumping the local hour hand. That suits someone checking a second zone from home more than a frequent flyer who changes local time every trip. Spinnaker does not publish an accuracy or power reserve figure on the product page, so we have left both out.

How well is it built?

The specification is strong for the money. Spinnaker lists a 316L stainless steel case, a sapphire crystal with anti-reflective coating, a screw-down crown and 15 ATM of water resistance, which is 150 m (the dial says 500 ft/150 m). Long Island Watch adds that the caseback screws down. The bezel turns both ways and uses a glass insert, according to Worn & Wound, and the applied indices carry Swiss Newlite lume.

The bracelet closes with a fold-over buckle with a safety lock and push buttons. That is fine, but there is no on-the-fly micro adjustment listed, so fit relies on links and spring bar holes.

Is it good value against its rivals?

The RRP is £448 on Spinnaker's UK site. For that you get sapphire, an automatic GMT movement, 150 m of water resistance, a bracelet and a spare strap. The closest rival is Spinnaker's own Bradner GMT, which uses the same kind of movement in a more vintage case and also lists at £448 in the UK (T3 reported £490 at its March 2024 launch).

Outside the brand, the Rotary Seamatic 300 GMT RGB10005/04 has an RRP of £349 for a 42 mm case with 300 m of water resistance and a jubilee bracelet, but no spare strap. The Orient Mako GMT has an RRP of £499.99 and carries an in-house Orient movement and a bigger brand name. The Fleuss sits between the two on price and beats both on the colour and the extras.

Spinnaker also runs frequent offers on its own shop, so it is worth checking before paying the full RRP.

What is the catch?

Size is the first one. At 43 mm and 190 grams it is a big, weighty watch, and the beads of rice bracelet adds to that. Second, the colour is loud by design: an orange-red dial under a blue and red bezel will not suit anyone who wants a quiet everyday watch. Third, Spinnaker does not have the resale value or the service network of Seiko or Orient, and the warranty is two years.

There is also little owner feedback on this exact model yet, so long-term reports on the bracelet and bezel action are thin. If a bright, well-specified travel diver with a spare strap is what you want, it is a good-value way to get one.

“A loud dial, a proper GMT movement and a spare strap in the box: the Fleuss knows exactly who it is for.”