The Speedmaster Professional X-33 is also known as the ?Mars Watch?. Standard analogue displays indicate the hour, minutes and seconds. The digital display, showing the time and date, also has countdown, chronograph and alarm functions. The special digital functions include mission elapsed time and universal time. The Speedmaster Professional X-33 was designed and tested over five years in co-operation with American, Russian and European astronauts, as well as professional pilots from the U.S. Navy`s Blue Angels and the US Air Force`s Thunderbirds squadrons. The watch integrates the latest technical features required by professional flight and space crew, including a 24- hour alarm sound system with a loudness of at least 80 decibels that is audible over the reverberating noises and echoes inside the space shuttle. In line with guidance from astronauts, the X-33 also has bigger and clearer numbers and letters on an enlarged digital display. To be ?flight qualified?, it is accurate to within -0.3 to +0.5 seconds per day. The X-33, which has a titanium case, is also water, pressure and shock resistant to high standards and can withstand extreme temperatures ranging from -20 degrees to +70 degrees centigrade. The name ?X-33? was originally used by Omega watchmakers as a code name in the development of the watch, but was kept on as its commercial name. This watch is published on pages 172-173 of ?The Master of Omega?.