The Grönefeld One Hertz is the second complicated mechanical timepiece created by Swiss-trained, Netherland-based watchmaking brothers, Bart and Tim Grönefeld. The movement for this new timepiece was created completely in-house. The dial indicates hours and minutes on a sub-dial at 2 o’clock. The power reserve is indicated at 12 o’clock.

What really makes this timepiece stand out, is the deadbeat seconds, which is indicated by the large off-center sub-dial. Independent deadbeat seconds, rotate the dial (independent means the seconds are displayed in the sub-dial) by ticking forward, much like on a traditional quartz movement. Except that this is a mechanical movement, which makes it more complicated to produce. In fact, this is the world’s first and only mechanical timepiece with independent deadbeat seconds.

Photo by Grönefeld.