The UR-105 TTH – “TTH” stands for Tantalum Hull – is a beautiful object, substantial and pleasing to hold. Its distinctive octagonal form features deep streaks along its entire length. It is angular, geometric, and symmetrical with strong influence from the Art Deco style. The UR-105 TTH comes with a protective cover, a breastplate that protects the mechanism. Tantalum is a perfect protective shield against corrosion. Hence its name Tantalum Hull. Activating the sliding “tongue” of the UR-105 TTH opens the hull to reveal its mechanics, featuring a satellite time indication built on a new skeleton carousel. The latter supports four-hour satellites, each displaying three-hour numerals that rotate in turn along the minute track, providing both analog and digital time displays.
A power reserve indication and digital seconds complete the information on the dial. The digital seconds displaying the seconds in ten-second increments is particularly remarkable. To make it as light and as ephemeral as possible, the seconds disk was made using the LIGA photolithography process and the marker is openworked. The total weight of the display is less than 0.10 grams.
On the back, two turbines regulate the movement’s automatic winding system, which can be easily adjusted using a small lever according to how active the wearer is. In the “FULL” position, the slightest movement of the wrist is enough to wind the mainspring. In “STOP” mode, the automatic winding system is deactivated and the UR-105 is manually wound. A third intermediate position, “RED” (for REDUCED), moderates winding to minimize excessive tension and wear.