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The HM9 Flow is a watch shaped like a land-speed record car, with a 51mm titanium hull that tapers at both ends and twin bubble domes where a dial would normally be. MB&F designed it as much for a rotating display stand as for the wrist, and that honesty about its nature is part of what makes it interesting. If you want a watch that does not look like a watch, this is one of the most committed answers anyone has produced.
Maximilian Busser launched the HM9 in 2018 as the ninth Horological Machine, and the Flow designation refers specifically to the aerodynamic bodywork inspired by mid-century streamliners and racing cars. The case profile is not a round or cushion shape adapted for drama; it is genuinely automotive, with a longitudinal axis and a cockpit layout that places the two movement displays under separate sapphire domes like a split-windshield roadster. MB&F has always treated its machines as collaborative sculpture, and the HM9 brought in exterior design thinking from outside the watch industry to achieve that silhouette.
The automatic movement inside was developed specifically for this architecture, routing its output to the twin displays rather than a conventional dial. Production has remained limited since launch, consistent with MB&F's practice across the HM line.
At 51mm in length and with an unconventional profile, the HM9 sits on the wrist more like a cuff ornament than a watch, and that is worth experiencing in person before committing. The twin dome sapphires are highly curved and difficult to replace outside MB&F's own service network, so any chip or crack is an expensive problem. Titanium wears well for everyday use but the case finishing on the HM9 is complex enough that polishing or restoration work requires the factory.
Resale liquidity is thin compared to major Swiss brands; you are buying into a collector market that is passionate but small, and exits can take time. Verify that the rotating display stand is included, as it was sold separately or bundled depending on retailer and period of sale.
New HM9 Flow examples in titanium have retailed in the $80,000 to $100,000 range depending on configuration and market. The secondary market has been relatively stable for desirable variants, though pricing is sensitive to condition and completeness of packaging. MB&F pieces hold value better with full box and papers, and the HM9 is not exception.
Expect meaningful discounts on examples missing the stand or with altered finishing.
The HM9 runs the MB&F HM9 automatic caliber, a movement engineered specifically for this case architecture and not shared with other references. Service must go through MB&F directly or an authorized service partner; independent watchmakers generally cannot source parts. MB&F has maintained a strong service reputation and offers a full restoration path, but turnaround times can run several months.
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Both turbine rotors on the HM9 must spin freely during wrist movement; a stuck turbine has a seized pivot.
| Area | What to check | What is correct | Red flag |
|---|---|---|---|
| movement | Twin turbine rotor freedom | Both turbines spin freely with wrist movement; consistent turbine rotation | One or both turbines stuck or slow; seized pivot |
| case | HM9 case profile | Case profile consistent with official MB and F HM9 Flow specification | Case profile variation; non-genuine or modified case |
| movement | 72h power reserve | Approximately 72h actual run time; consistent with HM9 specification | Run time substantially below 72h; worn or damaged mainspring |
