The BRK SC7010B photoelectric smoke and carbon monoxide alarm is a state-of-the-art 120 volt hardwired smoke/carbon monoxide combo alarm that features a photoelectric smoke sensing chamber and electrochemical carbon monoxide sensor. The spread spectrum horn tone has a lower and varying frequency that makes it easier for the elderly with normal age-related hearing loss to hear the horn. The end of life signal provides audible notification the alarm needs to be replaced. This alarm is interconnectable with other alarms, such as heat alarms or fire alarms and the "Quick-Connect" harness makes connecting to AC power quick and cost effective. Listed to UL 217 and 2034 standards, this alarm also uses 2 AA batteries as a backup, keeping you protected even during power outages.