Engine Fire Extinguisher

[WebMaster]

I have noticed in the advertisements for some aircraft, that they list as a feature an engine fire extinguisher system.
I have never seen this as an item for Skymasters, and yet it makes sense that you might want one, especially for the rear engine.

Has anyone seen such a thing for a Skymaster?? Would this be an STC, or a field approval? What would the agent be?? I see that Halon is falling out of favor.