Have anybody heard of an undercoat named fixotropic?

I wanted to add an undercoat to my new Magnum.

The dealer promoted an undercoat which he referred to as "fixotropic".

I have not found a brand called fixotropic.

After doing some e-research it seems like the term fixotropic is used for fluids that have high viscosity and seal the material well.

The dealer talked about a thin clear coat which self-sealed after being hit by a rock etc.

Does anybody know what he is talking about?