Vortex manipulator
From Tardis Wiki, the free Doctor Who reference
A vortex manipulator was a form of basic time travel developed by the Time Agency of the 51st century. Although it was generally used by the Agency, the Family of Blood stole one to follow the Doctor around the universe. (DW: Human Nature)
The Doctor considered it very primitive compared to a TARDIS, describing his TARDIS as a "sports car" to Jack Harkness's "space hopper".
Jack Harkness had his manipulator housed in a Time Agency wrist strap. (DW: Utopia)
