The First Alert 1042409 Photoelectric Smoke Detector 2 Pack is a brand new set of smoke alarms designed for home security. These white smoke alarms are powered by batteries and feature a photoelectric smoke sensor, battery backup, and voice alerts. With a diameter of 5 inches and a weight of 13.4 ounces, these detectors are easy to install and provide reliable protection against smoke and gas hazards. First Alert is a trusted brand known for its quality and safety products, making these smoke detectors a valuable addition to any home.