These air horns are in perfect working order, and they are loud as hell!
I have two sets for sale ($195 each).
They come with the original FIAMM air compressor. This is a sliding-vane type of compressor. I checked the impeller to make sure that the vanes slide okay. They're perfect.
Also included is the original FIAMM power relay. This relay works perfectly.
I pulled one of the horn sets these horns from my 1973 FIAT 124 Sport Coupe (which I no longer own). They've been sitting in my garage for decades, unused. I tested the horns, compressor, and relay. They are LOUD, and they sound as good as they did in 1973!
I rated them as "good", rather than "excellent" because they're not pretty and shiny. Mechanically, they are excellent and, once you install them, they're under the hood and out of sight.