Above Price is for 3 Pieces. Replace Old Model# i12010S-CA, 21027904 Worry-Free 10-Year Backup Battery – No battery changes for 10 years. Avoids inconvenient battery replacements over the life of the device. Interconnected Alarms – When one alarm sounds, they all sound, so you never miss an emergency and can get out faster. Self-testing Alarms – For added assurance, internal components ensure alarm is always operating as expected. Simple Installation – Easy install with included twist-and-click mounting bracket. End-of-life Notifications – This alarm beeps to remind you it’s time to replace it 10 years after it is powered. Power Source 120V AC, 60 Hz, with 10-year† sealed battery backup Surge Protection Meets the new ULC S531 4th edition 20kV surgetest, reducing chance of electrical fire Smoke Sensor Photoelectric Audio Alarm 85dB at 3m (10ft) Temperature Range 4.4˚C (40˚F) to 37.8˚C (100˚F) Humidity Range Up to 95% relative humidity (RH), non-condensing Wiring AC wiring, plug-in quick connector Cross Refefence i12010S-CA, 21027904 Warranty 10-Year Limited Warranty (battery included)