What Type Of Call Siren/Horn is this?

[x635 4,066]

Never seen something like this before. Used to call volunteer backup for a paid department in an urban downtown area.

[Bnechis 3,961]

That's the replacement PA speaker for this:

[SECTMB 612]

Looks like an old Chrysler air raid siren.

[recoiloperated 16]

Looks like an old Chrysler air raid siren.

http://en.wikipedia.org/wiki/Chrysler_air_raid_siren

[sympathomedic 383]

This is a Chrysler Vicotry Siren, powered by a V6 Hemi engine. www.victorysiren.com It does not spin like a regular siren, it compresses air. But the enitre unit does turn at 2RPM, though the one in the pic looks like it has been taken off its turntable.

Per the site, this thing produces enough power that it makes nearby dry grass smolder when they crank it up- the transfer of power from the engine to sound energy is that great.