A vortex manipulator was a form of basic time travel used by the Time Agency of the 51st century. It had additional capabilities as well. Time Agents were each given a vortex manipulator. Vortex manipulators used and issued by the Time Agency were housed in leather wrist-straps with a covering flap, enabling the device to be worn conveniently by the Time Agent without drawing attention to the device itself.
Although it was generally used by the Agency, the Family of Blood stole one to follow the Tenth Doctor around the universe.
Part of a series on the #Tech of Doctor Who
There is always Time for some Time Lord…
The TimeLord technology… it’s more than bigger on the inside