Fire Angel Optical Smoke Alarm 1 Year Replaceable Battery SB1-T 1 Year Replaceable BatteryThe Fire Angel SB1‑T Smoke Alarm has been designed to make protecting your home simple, with easy install and rigorous testing by independent parties, such as BSI Kitemark, to ensure quality and longevity.Optical SensorA fast response to slow burning fires.3 Year WarrantyManufacturer’s warranty for peace of mind. Slow Burning Fire Protection Optical Smoke SensingThe optical smoke sensing chamber works by ‘seeing’ smoke as it enters the alarm ‑ making it perfect for slow burning fires where there is thick white smoke. For the fastest response to all fire types search for Fire Angel Thermoptek Alarms.Battery Powered Protection1 Year Battery IncludedThe unit is provided with one 9V battery which will last around a year and can then be replaced. For a decade of protection look for our range for Fire Angel Smoke Alarms with a sealed, lifetime battery which will protect you for 10 years.Testing Made SimpleAs well as allowing easy testing with a sweeping brush from the floor below, this large button also activates our Sleep Easy function which silences low battery chirps for 8 hours ‑ giving you a peaceful night’s sleep.