It contains three different lasers. The first laser is a microwave-powered laser particle beam, the second laser is a laser-guided high-pressure water cannon, and the third one are some pieces of steel wool that have a laser. When turned on, the microwave-powered laser shoots out a green colored laser, the water cannon shoots out water, and the steel wool laser shoots out a yellow colored laser. The device also has the ability to cross the laser beams.
In order to remove a dirty spot on a plate, SpongeBob invents the Spot-Master 6000. Later, when SpongeBob sets the Spot-Master 6000 on maximum power, the Krusty Krab explodes and the invention disintegrates.
The Spot-Master 6000 may be a reference to the Ghostbusters series; in the movie they use nuclear accelerators and "cross the streams" as the Spot-Master does.