THERMOPTEK TECHNOLOGY: The FireAngel ST-622 Thermoptek smoke alarm uses patented multi-sensor optical smoke alarm technology making it a reliable choice among fire alarms for home. LONG LIFE BATTERY: Powered by a 10 year sealed lithium battery, this standalone FireAngel smoke alarm provides dependable performance, featuring an End of Life indication that reminds when the unit should be replaced. LARGE CENTRAL BUTTON: Designed with a large central button for Test and Smart Silence, this smoke alarm can mute a known nuisance alarm for 10 minutes while the smoke detectors for home continue monitoring smoke levels. EASY INSTALLATION: Installation is simple with automatic battery engagement on the base plate. Built-in bug mesh and dust compensation help reduce false alarms, ensuring consistent performance of your smoke alarms for home.