Battery Operated Smoke Alarms, Smoke, Ionization, 4 in Diam

Features: Test button - Tests unit's electronic circuitry, horn and battery function | Low battery indicator - Smoke alarm will chirp in the event of a low battery | Red LED - Flashes every 30-40 seconds to indicate that the smoke alarm is receiving power | Dust cover | Battery operated - Easy installation and continuous protection even during power outages