What is the most mysterious siren?

[MackinacFudge5]

I've got a few ideas:

ACA 3-Signal Hurricane 130
ACA Screamer 105
ACA Pre-Cyclone 120 (advertised version)
ACA Performance Plus Series (NOT the ASC versions)
Whelen WS-2500
Whelen WPS-4000 II
Whelen WS-280 Series (as opposed to the Vortex O which later became the older OmniAlert which THEN became today's OmniAlert)
Sentry 10V2T-3S
Sterling Super Quad
Federal Electric Type B Quad Head
Federal Electric Fedelcode Type Mach 10
CTI/Storm Master sirens
Gamewell Codewell
British General Electric Sirens
Japanese Motor Sirens
Bell "Freewheeling" sirens

[jacob585]

I'd say the AL-12000 is a good contender, this was the bigger brother to the already extremely rare and poorly documented AL-7200 and doesn't even have any photos or advertisements to my knowledge.

[HDN]

How about the siren used on the German Ju 87 Stuka dive bomber from WW2? I haven't found any detailed drawings or pictures of the thing besides the ram air turbine for it.

[fullsendersonly]

the B&M vertical siren is extremely rare and almost no data is known about it except the years produced and installation years and modifications.

[CincyTboltman]

The Hor Sirex No. 15. Not too much is known about them. They were a single headed rotational version of the Super Sirex and only one exists in Hamilton, OH that was installed in 1954.

[Heathtypek]

I feel like it is the "B&M Model 20" there is 1 unit in SoCal that I’m trying to get. There is not a lick of information on it, even though it seems like a "B&M Vertical Siren” it’s chopper is completely different and the motor is way larger.

[Dorianelevator]

CICCA/Chollet "small horn no bevel gear"
only one of its kind known to exist in Barjols, France
it is a mystery on how many ports it has and had 7 horns before one fell off
it is a total mystery for the french community and likely is for you guys aswell