The PLR changes the genetic configuration of an individual, turning them into a different creature.
Depending on how updated the PLR is, the forms granted by it can range from Neopian forms to Pokemon to anthropomorphic creatures.
It could also be used to kill a Seachi, owing to their weaknesses to such effects.
A Pocket Lab Ray looks similar in all effects to a small ray gun. On the butt of the ray, where there is normally a hammer on a regular gun, there are two dials: One for race, and (in the case of Neopians) one for color.