Engine-uity

The HM4 has an incredible relationship between case and movement. Each made to work exclusively together; they are still separable in their beauty. Like Ferrari with an open window over its engine, the Thunderbolt's engine window is comprised of five custom cut sapphire crystals, three of which are solely dedicated to showing off the movement within the case. An incredibly hard-to-manufacture tubular sapphire crystal is positioned in the middle of the watch, inside both of the pods. This feature demonstrates the apex of MB&F’s education in sapphire crystals, offering an amazing cross-section view of the inner workings of a luxury timepiece machine. There are also sapphire crystals over the top and bottom of the case, as well as over each dial. Nothing about the HM4 seems hidden. From all angles there is both a view of the case and the movement inside of it – as they are meant to be appreciated together.