The BRK hardwire smoke alarm with photoelectric sensor is designed to reduce common "nuisance" alarms. It"s an excellent choice for installations in or near kitchens, near fireplaces, or in hallways directly outside bathrooms, utility rooms, or other areas prone to steam. This alarm is also a popular choice for hotel/motel applications. The 7010 AC-powered smoke alarm with photoelectric sensor includes these features: Photoelectric sensor which is more effective at detecting smoldering fires which smolder for hours before bursting into flame. 120-volt AC inter-connectable (with maximum 18 compatible devices). The alarm can be interconnected with up to 12 other compatible smoke alarms and six compatible devices like bells, horns, repeaters and door closers. If one unit triggers an alarm, all smoke alarms in the series will sound. Power indicators show which unit in the series initiated the alarm. Quick plug-in power connector for easy installation. Alarm indication which in an interconnected system, automatically identifies which unit initiated the alarm. Optipath 360 technology allows 360-degree access to the layer of air on the ceiling or wall that carries the fire signatures (smoke, combustion particles and volatile components). Single test/silence button which both silences a non-threatening alarm or low battery warning and allows you to test the unit"s functionality. Locking feature for tamper resistance. 10-year limited warranty. All BRK Electronics smoke alarms meet UL 217 standard and are listed with the California State Fire Marshal. They use the new UL mandated repeating 85-decibel alarm horn pattern. 10-year limited warranty.--Bree NorlanderWhat"s in the Box One smoke alarm and user"s manual