I am really trying really hard to find this Siren, I would like to know the siren for this - 

I'm shit with sirens, but it sounds like an FS Smart Signal to me.

Here's a link to the siren for IV. 

 

The direct link, in case you don't want to click through to the video for whatever reason. 

 

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If your talking about the unmarked car then it sounds like a Whelen(CHP's Siren) 

But i could be wrong

It sounds like a Smart siren's manual wail with rumbler.

If your talking about the unmarked car then it sounds like a Whelen(CHP's Siren) 

But i could be wrong

 

 

Definitely not a Whelen and not a CHP siren. It's the FS Smart Siren with Rumbler. that's what the NYPD uses. And CHP doesn't use Whelen Sirens either.

I dont think the unmarked doesnt sound like the Federal SS , It sounds way different, close to the CHP one

Heres another vehicle 

 

It's like a higher pitched CHP yelp siren.

Any link to it ?

 

The same siren -