Zenith For Only Watch 2013, the Manufacture Zenith will introduce a unique piece, the Felix Baumgartner Stratos Prototype I/I. One-of-akind model developed by the Manufacture and the only prototype ever produced to develop and test the El Primero Stratos designed for Felix Baumgartner and which has become the first-ever supersonic watch. In 1969, Zenith effectively launched the El Primero calibre by placing it on the landing gear of a Boeing 747 on the famous Paris-New York flight. Fully living up to the high expectations for this legendary movement, the watch was running as smoothly upon arrival as it had at the time of departure. In 2012, it was from even higher, on the very edge of space, that Manufacture achieved a new historical feat as the creator of the very first watch to break the sound barrier (attaining a speed of Mach 1.25) in direct contact with the exterior. Insulation between the case and the movement prevents heat loss stopping the movement, and an elastic ring around the glass keeps it in place when the case contracts. Tests at minus 78° C showed that the low conductivity polycarbonate glass was not necessary. The pressure tests on the case were beyond the normal 100 meters to survive the near vacuum of the stratosphere. The impact tests were at 5,000 G. The case used for the jump is like the standard steel case. The only difference in the movement was the all-silicon escapement. Except for the extra-long strap to fit over the space suit, the watch is the same as those for sale. This strap is fitted to the watch sold at the Only Watch auction.