Kidde i9080 Battery Operated Smoke Alarm with Safety Light Suitable for hallways and stairwells. 9 Volt batteries required (best with Polaroid 9 Volt batteries) Lights escape path to help guide your family to safety Hush feature temporarily silences nuisance alarms Test button test unit's electronic circuitry, horn, safety light and battery functions Red LED flashes every 3-40 seconds to indicate that the smoke alarm is operating