Thimble of Rassilon
From Tardis Wiki, the free Doctor Who reference
Attending the opening of a new Capitol building as Lord President, the Fifth Doctor donned the Thimble of Rassilon as part of a Presidential dress he was forced to wear. While seen as ridiculous by the Doctor it proved useful in securing the Capitol TARDIS within a time loop, seemingly able to stablise the loop indefinitely. (AUDIO: Time in Office)
