BRK SMCO100V-AC Interconnect Hardwire Photoelectric 2-in-1 Smoke & Carbon Monoxide Alarm with Battery Backup Voice. Features voice warning with location, voice tells what the danger is and its location. Includes advanced sensing technology for early warning and less cooking nuisance alarms. Easy install & battey replacement, add protection in minutes. A battery pull tab is also included to keep the batteries fresh until the home is occupied. Interconnects with most First Alert and BRK hardwired alarms. When one alarm sounds, all compatible alarms sound (up to 12 smoke alarms and 6 other CO/heat alarms). Battery backup for protection during power outages. A dust cover, keeps the alarm clean during construction.