The Kidde Smoke & Carbon Monoxide Detectors are powered by AA batteries, making them convenient for installation in various locations around the home. With a photoelectric smoke sensor and voice alerts, these detectors provide reliable protection against smoke and gas hazards. The pack includes 4 detectors, each with 2 batteries included, ensuring comprehensive coverage for maximum home security. Easy to install and designed to save lives, these white Kidde detectors are a crucial addition to any household.