Presenting:
The Ghostbusters Giga-meter
From it's first sighting in Ghostbusters II it makes you go "Hey
what's that". The Giga-meter upstages the PKE meter by use of it's
spinning light show provided by it's scanning head. As an added
surprise the two probes that stick out the front also wave and light
to collect ethereal energies. The main readout reads on GeV's. GeV
stands for Gigaelectron Volt and is the standard unit used for mass
or energy in high-energy physics.

Let's take a look at the filming prop:
It was also seen within Star Trek VI without the
peripheral head:
The original prop was built from an off the shelf
battery powered scrubber manufactured by the
Redman Corporation entitled the Power Scubber
Buffer.
Giga-meter page
two