hey tony,
that is the demon instrument voltage regulator sold by redfish above. ^^^
http://www.DeMonIVR.com/
"Solid state regulators provide advantages other than no moving parts. Their output voltage is constant at 5.02 volts. Overload and short circuit protection features are built in. They cannot send 12 or more volts to the gauges, (possibly frying them), or send less than 5 volts (resulting in low or wrong readings), or cause wild needle swings (one of many malfunctions known to mechanical units)."
