An Oplink Security SRN1300 Emergency Siren is an accessory add-on unit for use with an Oplink AlarmShield or TripleShield system. The Emergency Siren is the piercing voice of the security system as it lets intruders know they"ve been caught and alerts anyone in the nearby area that something has happened to trigger the siren. The siren emits a blaring 110 dB alarm when activated to sound by the Oplink Processing Unit (OPU) as a result of a triggered sensor. A siren can be installed up to 90 feet from the OPU and you can add as many sirens to your system as you feel you need. The Emergency Siren is powered by an AC power adapter.Note: This siren is only compatible with Oplink Security Systems.