Kidde KN-COSM-XTR-B Nighthawk Combination Carbon Monoxide, Fire, and Smoke Intelligent Alarm (4 Pack) Voice alarm, announces hazard type detected helping to speed up correct reaction to hazard detected Combined carbon monoxide and smoke alarm, single unit can be installed instead of two, reducing installation time Test reset button tests alarm circuitry and triggers voice announcement, flashing green and flashing red LEDs Low battery condition announcement initiates alarm chirp and flashing red LED activation Battery powered, provides protection even during power outages