Real innovation in watchmaking is rare, which is why Parmigiani's new concept—with a 70-day power reserve—is so exciting.

It's rare that there's a genuine innovation in mechanical watchmaking. Sure, every brand loves to talk about the latest thing they've done, but it's usually more surface level than a true advance in the underlying technology. Parmigiani, though, is showing something entirely new in its Senfine concept watch, which keeps time using a totally new mechanism that allows for a 70-day power reserve. Yes, 70 days. (Most watches run only two or three days at a time before needing to be rewound.)

To understand what makes the Senfine special, you must first understand the basics of what makes a mechanical watch work.

The mechanism that actually ticks out the fractions of seconds is called the escapement, and almost all watches use a style called a "lever escapement." This was invented back around 1755 by a British clockmaker, and since then it's been shrunk down to fit on the wrist. But otherwise nothing has changed. A balance wheel with a spring in the center swings a wide arc (usually around 300 degrees, give or take) causing a little fork to flick back and forth on a gear, letting it slowly advance one tooth at a time. Most watches today advance three or four times per second, getting you the little ticks you hear if you put the watch up to your ear.

Only a handful of watch brands, most notably Omega, don't use this basic mechanism in their watches. Omega uses something called a co-axial escapement, which is meant to improve on the lever escapement by making it more reliable, more accurate, and more durable. It's the same basic principle, just done better.

The new Senfine escapement does away with the lever escapement's mechanics for something much more efficient. There's still a wheel, but it swings only 16 degrees instead of 300—and does so 16 times per second instead of four. The increase in frequency means you get much higher accuracy than with a traditional balance, and the low amplitude conserves power (there's a lot less motion happening overall, meaning less power is used). To make this work, the little fork (usually made of metal and cut rubies) is replaced by silicon blades. The result is a mechanical movement that, according to the company, is capable of getting that incredible 70-day potential out of the same type of mechanical spring that gives a typical watch 48 to 72 hours of juice