Detects both carbon monoxide & smoke in a single device, it is designed for hardwired installation but features a 10 year battery back up that allows the unit to function in the event of a power outage, carbon monoxide smoke detector can be connected to other compatible brk or first alert carbon monoxide smoke detectors within a single family residence, single button silences or tests the unit, hard wired with battery back up, electrochemical/ionization sensor type, note: please check your local building code requirements before installing this product to determine compliance with applicable standards.