100W 200W Auto Alarm Hooter DC12V Police Car horn siren speakers is a loud noise making device. 100W 200W Auto Alarm Hooter DC12V Police Car horn siren speakers are mounted in fixed locations and used to warn of natural disasters or attacks. 100W 200W Auto Alarm Hooter DC12V Police Car horn siren speakers are used on emergency service vehicles such as ambulances, police cars, and fire trucks.