Kidde Ionization Smoke Detector with Battery Backup is an ionization-sensing alarm that offers 120 VAC of power with a 9-Volt battery backup for continuous protection during power outages. This alarm can operate as a single unit or as a component of an inter-connected system in your home or business. This important safety device has a push-button test capability to check its circuitry, horn and battery and can be put into a hush mode that will silence nuisance alarms. This unit has a tamper-resistant locking feature to help prevent unauthorized entry or theft.