Kidde KN-COSM-IBA 21006377 Hardwire Combination Smoke/Carbon Monoxide Alarm, 2-pack Talking alarm announces the hazard type detected, helping to speed up reaction time Combined carbon monoxide and smoke alarm, a single unit can be installed where previously two were needed Battery safeguard ensures the unit cannot be accidentally mounted without batteries Test-reset button tests alarm circuitry and triggers the voice announcement Meets safety standards set by Underwriters Laboratories (UL) and interconnects with other KN-COSM-IBA models