Model 0914. Discreet design with state-of-the-art protection. Battery operated. 9 Volt battery included. Test button. Low battery indicator. Easy installation. Kidde recommends for maximum protection that both ionization and photoelectric smoke alarms be installed. Ionization technology is faster at detecting fast flaming fires that give off little smoke. Photoelectric is faster at responding to slow smoldering, smokey fires. Compact 3-7/8 inch size offers maximum protection - More visually appealing than larger, bulkier units. Loud, Piercing 85 Decibel Horn - Alerts you quickly. Flashing Red Light - Indicates alarm is receiving power. Test Button - Checks horn, battery and alarm circuitry. Low Battery Indicator - Alarm will sound a warning chirp if battery is low. Easy Installation - Quick-connect mounting bracket installs in seconds. Permits simple twist off removal of unit for battery replacement. Complies With the Following Authorities: Underwriters Laboratories (UL); Federal Housing Authority (FHA); Housing and Urban Development (HUD); National Fire Protection Association (NFPA); California State Fire Marshal. The National Fire Protection Association recommends smoke and fire alarms for every room or area of the home or building: All floors, basement/rec rooms, occupied attics; all sleeping areas; plus at each end of hallways more than 30 feet long. This product is designed to detect products of combustion using the ionization technique. It contains 0.9 microcurie of Americium 241, a radioactive material. 3 Year Limited Warranty.