First Alert SA305CN Smoke Alarm with Long Life Lithium Battery

The First Alert SA305CN/SA305FF Ionization Smoke Alarm is an ideal choice for essential smoke detection. This smoke detector uses ionization smoke-sensing technology with an enhanced smoke-gathering design that is great for detecting smoke from flaming fires. A loud 85-decibel alarm is designed to wake even the soundest sleepers. Convenient single-button operation lets you silence false alarms and test the alarm to ensure it is working. The alarm is powered by a single 9-volt battery, features convenient side-load battery installation, and includes a theft-prevention lock that prevents the battery and/or the alarm from being removed without proper tools when the lock is activated. A blinking light shows you the alarm is operational, and a low-battery alert lets you know when it's time to change the battery.