The Proton Beam is a standard looking design with red add-on wires. (The player does not see the weapon during game play per se, only the color switch.)
The Proton Beam has a great fire range and is most effective against red paranormal entities, and the bosses of the game. It can also snare a ghost and wrangle them.
Updates from Standard Proton Gun
One new feature is the ability to cross the streams of the Proton Beam with other Ghostbusters without causing an epic event.