I need to know the identity of a part that I think is a varistor.  It is dark
red, looks similar to a disc ceramic capacitor and has the markings:

H A3
175L10

On the circuit board, it has a reference designator of RV1.

Does anyone have an idea who the manufacturer might be and what the device
is?  I think it is used for surge suppression in the circuit.

I really appreciate any help from anyone.

Max