Infinity Ring (Device) is the time travel device invented by Dak's parents and was finished by Sera in A Mutiny in Time. It is the most important component to the Infinity Ring Series because it holds so much power on whether they stop the Hystorians and fix the breaks or help them or not do anything with it at all and let Cataclysm occur. It also lets them warp through time. The only Hystorians agent that came the closest to destroying the ring is the Caliphe  Vizier  of Baghdad in Cave of Wonders.

Tilda a.k.a The Lady in Red and the leader of the SQ organization ,stole the Infinity Ring in Behind Enemy Lines in the year of 1943 and took it back to her time to be replicated ,making her own Infinity ring ,which she calls the Eternity ring. She used to ring to travel back in time to ancient Greece during the time of the great philosopher Aristotle to kill him in order to prevent him from forming the Hystorians.