Shop First Alert dual sensor alarms designed to provide reliable early warning for different types of fires. Featuring photoelectric and ionization sensing, these smoke alarms help detect both smoldering and fast-flaming fires while providing dependable protection for your home. Protect your home with a First Alert dual sensor alarm designed to detect both smoldering and fast-flaming fires. Dual photoelectric and ionization sensors provide broader fire detection, while loud alerts, test and silence controls, and available battery-backup models help provide timely warning when it matters most.