and an Overvolt relay..
These are examples of components often encountered on GA aircraft.
The Lamar regulator is clearly marked and it can be easily seen what it is all about. They are often found on Piper singles, and throughout the range at that.
The overvolt unit can be seen on Cessna's and even some Islanders.
They are not precision devices, - the operating points (voltages) can be somewhat variable and indeed the Lamar depicted is adjustable.