Some people think of the wristwatch simply as a functional keeper of time. Some, like the makers of the HM4 Thunderbolt, turn horology into an art.

Three years of development and 311 custom components later, MB&F has created this aviation-inspired timepiece, crafted out of titanium and sapphire. Hours and minutes are displayed on the right “engine,” while the left displays the 72-hour power reserve. A black hand-stitched calfskin strap keeps the piece firmly but comfortably in place, though it’s worth noting that the moving internals can be seen both from above and below the body of the watch.

MBandF.com