Kidde 21026045 AC Hardwired Wireless Interconnect RF-SM-ACDC Smoke Alarm Makes it easy to expand the coverage of a current interconnected system When one alarm sounds, they all do: 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 are included, allowing it to be used with most existing interconnected systems Smart touch button quickly and temporarily silences nuisance alarms