First Alert COMBOV Combination DC Smoke & Carbon Monoxide Alarm with Voice Alert Voice & Location Tech: Sounds Alarm and tells you the location and potential danger. 2 in 1 combo alarm: More protection in one alarm, smoke/fire & Carbon Monoxide New slim design: half the height of the standard alarm Photoelectric smoke sensor for Maximum protection. Loud 85dB alarm. power LED and alarm indicator. Battery powered 2AA included.