Allowing us to take flight for the very first time, the ‘Thunderbolt’ started MB&F’s HM4 series inspired by twin-engine jet airplanes. It represents the culmination of four long years of intensive development ending in a completely radical design and an unconventional movement composed of 311 components – each one developed specifically for this calibre.
The 18k red gold case is just as complex. The transparent sapphire crystal section required over 185 hours of machining and polishing to transform an opaque solid block of crystal into a complex, exquisitely curved panel allowing the light to come in and the beauty of the HM4 engine to stand out. Incredibly complex, the HM4 is disarmingly user-friendly: one dial displays the time, while the other displays the power reserve – just like a cockpit’s speed and fuel gauges.
Both the aviation-inspired case and the specially designed engine seduced the jury of the Grand Prix d’Horlogerie de Genève, bringing home the Best Concept & Design Prize in 2010. The HM4 RT in red gold and titanium arrived a few years later in 2012 and is limited only to 18 pieces.
18k red gold and grade 5 titanium and sapphire case
Dimensions: 54 x 52 x 24 mm
Three-dimensional horological engine developed with Laurent Besse and Beranger Reynard
Manual winding with two mainspring barrels in parallel
Power reserve: 72 hours
311 components / 50 jewels
FUNCTIONS / INDICATIONS
Hours and minutes on right dial, power reserve indicator on left dial.
Five sapphire crystals: 2 x dials, 1 x central case section, 2 x display panels (top and bottom)