Kidde 1279-9999/RF-SM-AC Hardwire Smoke Alarm with Battery Backup, Interconnectable Wireless technology uses radio frequency to both transmit and receive messages about a hazard in the home AC power with battery backup enables homeowners to expand a current interconnected system Two universal adapters included allowing it to be used with most existing interconnected systems Smart touch button quickly and temporarily silences nuisance alarms Kiddes smoke alarms meet the requirements of Underwriters Laboratories (UL), an independent facility that tests products for compliance with widely-accepted safety standards