6 in.x 6 in. x 1.7 in. Made of plastic. 9-V battery included. Ionized technology. Better at detecting fast flaming fires. Easy installation. Accessible without cover plate removal. Test button. Circuitry testing and alarm operation hush button check-up. Quickly silences nuisance alarms front loading battery door. Quick battery change, without alarm removal. Tamper resistant. Locks the battery door compartment, preventingthe removal of batteries for continuous protection low battery indicator. Warning sound, when battery needs to be replaced. White.