First Alert SA511CN2-3ST Smoke Alarm, 2 Pack Help keep your family safe with these battery-operated smoke alarms that wirelessly interconnect with each other and other First Alert enabled alarms so that all sound when one is activated, creating a home safety network; comes in a pack of 2 alarms Voice alarm with 11 programmable locations tells you where the danger is so you can choose the best evacuation route; loud, 85-decibel siren sounds to alert you to danger Equipped with photoelectric smoke sensor optimized to detect larger smoke particles produced by smoldering fires; helps minimize the number of false alarms Battery-powered alarm requires no rewiring for installation and provides continued monitoring even if there's a power failure; use with Polaroid AA batteries for best results Wirelessly connect up to 18 First Alert enabled alarms for the maximum in whole-home protection; includes test/silence button, low-battery warning, end-of-life timer