The Kidde PI2010 features Hush, allowing you to quickly silence nuisance alarms and also includes a tamper resist features that deters tampering and theft. The PI2010 includes a quick connect power harness that allows for quick and easy installation.Ionization Sensor may detect invisible fire particles (associated with flaming fires) sooner than photoelectric alarms.Photoelectric Sensor may detect visible particles (associated with smoldering fires) sooner than ionization alarmsInterconnect Interconnects with up to 24 Kidde devices on one wiring network of which 18 can be initiating.Battery Backup (9V battery included) Provides continuous protection even during power outages.Tamper Resistant Deters from tampering or theftHush Feature Temporarily silences nuisance alarmsRed LED Flashes every 30-40 seconds to indicate that the smoke alarm is operating properly.Test/Reset Button Tests smoke alarm circuitry and horn