The Hyposlip Travel system was a type of starship engine invented by the Brothers Hop Pyleen on the planet Rex Vox Jax. (TV: The End of the World) One type of engine, the Hyposlip 500 lightspeed podule, was greatly coveted by other races in the galaxy. Astro-race pilot Skip Pyleen attempted to sell the secrets of the Hyposlip-500 technology to the Rakkonoids, but was stopped by the Tenth Doctor. (COMIC: Death Race Five Billion)