TAG Heuer Monaco V4 is not a new watch. In Baselworld 2004, TAG Heuer took the watchmaking world by surprise when it launched a revolutionary concept-watch. The mechanical Monaco V4 overturned basic watchmaking principles by featuring driving belts and ball-bearings instead of the conventional wheels and pinions.

After 36 months, the first pre-series prototypes were officially presented at Baselworld 2007.

According to the news, TAG Heuer is timing the release of the V4 to coincide with the company's 150 year anniversary. The Monaco V4 will be the world's first mechanical watch with a "belt-driven movement and linear winding mass". The V4 will be produced in a very limited edition of only 150 pieces, has been in the making for 5 years.

A ingot slides back and forth in a central channel at the back of the watch, capturing power from the wearer's wrist movements. The ingot is machined with teeth along one edge that engage a cog at the side of the channel, rotating it with each pass.

Four synchronized barrels, each containing a metal spring, store enough energy to run the V4 for 50 hours. The barrels turn the movement using 13 0.5mm wide belts tightened with minuscule turnbuckles to a tension far beyond what jeweled pinions could sustain.