File:Sirena allarme antiaereo SIIS Ultravox.jpg - Wikimedia Commons

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Civil defense siren - Wikipedia

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Sirens that would have alerted a nuclear emergency being removed from cities around San Onofre – Orange County Register

Category:Warning sirens - Wikimedia Commons

Category:Warning sirens - Wikimedia Commons

Category:Ultravox - Wikimedia Commons

File:Belleville ACA Allertor 125 Civil Defense Siren - panoramio.jpg - Wikimedia Commons

Modulator, AirRaidSiren Wiki

Category:Warning sirens - Wikimedia Commons

SSTX3-MV is an explosion-proof electronic siren capable of producing three high decibel tones from the same unit.

SSTX3-MV Explosion-Proof Remotely Selectable Electronic Siren