"The First Alert BRK SC7010B Hardwired Smoke and Carbon Monoxide Alarm includes a battery backup so it keeps monitoring safety even if there's a power failure. This connectable alarm can be linked with up to 18 compatible devices (sold separately) so when one triggers, all alarms sound. It emits a loud, spread-spectrum 85-decibel alarm. It's equipped with electrochemical CO-sensing technology, and a photoelectric smoke sensor to help detect slow, smoldering fire. One button silences nuisance alarms and tests detector functions, while lights indicate if the threat is smoke or carbon monoxide. The latching alarm indicator identifies which unit initiated the alarm, even after conditions that set it off have subsided. And an end-of-life signal chirp lets you know when it's time to replace the unit. Hook up to AC power with the ""quick-connect"" wiring harness for easy installation. Gender: unisex."