Featuring a low-profile, contemporary design, the First Alert Slim Battery-Operated Photoelectric Smoke Alarm provides the same protection as a standard smoke alarm while taking up only a fraction of the space. This slim smoke alarm uses an ultra-reliable photoelectric sensor to detect smoke from slow-burning, smoldering fires, and it features a patented smoke entry system that allows a direct path to the sensor for more reliable detection. The battery-operated smoke alarm requires no hardwiring for installation, making it an ideal solution for those who want to enhance fire safety without hiring an electrician. The simple twist-lock mounting system installs easily onto a wall or ceiling, while the tamper-resistant locks help prevent removal of the battery to keep the alarm secure. Half as thick as a standard alarm, the smoke detector has a sleek, slim design that blends in seamlessly with most decor. A loud 85-decibel alarm sounds when smoke is detected, and a convenient test/silence button lets you easily check alarm function and mute false alarms.