The First Alert SA320CN Dual-Sensor Smoke and Fire Alarm is an advanced smoke detector that uses ionization and photoelectric sensors to provide early warning of both smoldering and flaming fires. Intelligent sensing technology helps to reduce false alarms from household triggers such as cooking smoke or shower steam. The battery-powered fire alarm installs quickly and easily with no wiring required. A loud 85-decibel siren is designed to alert even the soundest of sleepers, and a single button silences and tests the unit. Plus, it ships in frustration-free packaging so you can install it immediately.