BRK Hard-Wired w/Battery Back-up Electrochemical/Photoelectric Smoke and Carbon Monoxide Detector 1The First Alert SC7010BV Hardwired Combination Smoke and Carbon Monoxide Alarm with Voice and Battery Backup delivers both smoke and carbon monoxide detection in a single unit. Equipped with a photoelectric smoke sensor and an electrochemical CO sensor, it accurately detects smoke produced by smoldering fires and carbon monoxide leaks from multiple sources. If a threat is detected, the alarm emits a spread spectrum horn tone that is designed to be