Sash of Rassilon

The  gave those who wore it protection from the gravitational and energy forces which emanated from the Eye of Harmony. It also offered some control over the Eye itself. However, it had less power than its reputation suggested and would not have saved the Master had he opened the Eye fully. (TV: The Deadly Assassin)

It was one of the many Artefacts of Rassilon which were given to a newly elected President of the High Council. It was also a sacred item and the Time Lords bowed down to it. (TV: The Invasion of Time)