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Haute horlogerie is (usually) a very restrained and serious business; however one of Maximilian Büsser’s main goals in creating MB&F was to bring a child's sense of awe and playfulness into high-end watchmaking… mission accomplished with the HM3 Frog!

The HM3 Frog is crafted in titanium or zirconium, combined with a 22k gold “battle-axe” winding rotor. A close inspection of the case reveals carefully thought out detailing including distinctive clover-head screws and a figure 8 engraved around the domes that mirrors the form of the display back. The hours and minutes revolving domes complication, framed by an oversized date wheel, was designed by Jean-Marc Wiederrecht. Machining those aluminium and sapphire domes posed a number of technical challenges.

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HM3 Frog

the machine


  • HM3 Frog Ti in grade 5 titanium
  • Material: grade 5 titanium, black PVD zirconium with 18k yellow gold screws
  • Dimensions: 47 x 50 x 18 mm


  • Three-dimensional horological engine designed by Jean-Marc Wiederrecht/Agenhor.
  • Powered by a Sowind base
  • 22k gold battle-axe shaped ‘mystery’ automatic winding rotor.
Hour and minutes information transmitted via ceramic ball bearings to rotating domes.
  • 304 components / 36 jewels

Functions / indications

  • Hour on one dome (aluminium dome rotating in 12 hours)
  • Minutes on second dome (aluminium dome rotating in 60 minutes)
  • Date around the movement
download manual
Sapphire domes

Sapphire domes

Crafting the semi-spherical sapphire crystal domes is incredibly demanding; any slight imperfection would introduce a disconcerting magnification effect. The crystal needs to be perfectly shaped and polished to be absolutely uniform.

Rotating domes

Rotating domes

The paper-thin domes are machined from solid aluminium, chosen for its optimal strength to weight ratio: they weigh in at a micro-light 0.5g, reducing energy requirements to an absolute minimum.

Ceramic bearings

Ceramic bearings

Placing the rotor and regulator on the dial side required an inverted movement, only possible thanks to two large ceramic bearings that efficiently transmit time up to the revolving hour and minute domes.



The protruding eyes of real-life frogs enable them to see in many directions without having to turn their head. HM3 Frog’s bulbous hour and minute domes create a similar, but reversed effect: the wearer can easily read the time from a variety of angles without having to turn their wrist.


Horological Machine N°3 Frog is available in 2 versions