The Rejuvenation Shower is a technology aboard Red Dwarf discovered by Kryten and used by the Boys from the Dwarf. In theory, it was used to restore youth in a human, although if installed incorrectly it could be used for time travel. However the latter only occurred erratically, and this form of time travel was unstable. The instructions read: "With just an Allen key and a Phillips-head screwdriver, assembly should take no more than three hours. Please consult diagrams 1 through 369 for further instructions. Do not forget to install the alignment bracket." (RD: Lemons)