Reveals ghosts when transparent
The Ecto-Strobe was a air flashlight type device that serves various purposes. When it was first introduced, it's light could reveal if a ghost had been around the place the light was shining on in the last 24 hours. The Ghostbusters used this feature to clear Tracy the Gorilla's good name after he had been framed by a Ghost duplicate. During that same mission, Eddie Spenser Jr. used the Ecto-Strobe to disorient Count Grumpette by flashing the light straight into the Count's eyes.
Further more, the Ecto-Strobe is able to get ghosts out of objects, and even to Dematerialize some ghosts.
The Ecto-Strobe was first used in the episode Going Ape.