The Kidde 29HD Battery Operated Optical Smoke Alarm Twin Pack - White provides reliable fire detection for multiple areas of your home. Each alarm features a loud 85dB alert and a photoelectric sensor that is highly effective at detecting slow-burning fires while remaining less susceptible to false alarms from cooking fumes. These easy-to-install alarms include a hush button for nuisance alarms and come with 9V batteries and a 3-year manufacturer's warranty.