ACCURATE WITH LOW FALSE ALARM RATE: The fire alarms smoke detectors adopts photoelectric technology to detect smoke. More sensitive to light smoke and slow smoldering fires and can issue alerts faster and more accurately. Keep your home safe 24/7 EXTRA LOUD SOUND AND LED ALARM: When the smoke alarm detects smoke or detect combustion particles in the air, it will sound their alarms and the red LED will flash rapidly.Protect family and property safety in time EASY INSTALLATION: The wireless smoke detector can easily install with mounting bracket. No hardwired anymore and you can install it wherever you want(Avoid placing near the bathroom or kitchen) SIZE: 3.54in diameter x 1.57in depth. Home fires start every 83 seconds, Fire detectors for home can quickly identify fires and sound an alarm and allow the family to flee quickly BATTERY OPERATED SMOKE ALARM：2 x 1.5V AA Batteries (not included) for power supply of smoke detectors. Save you the trouble of wiring and provide uninterrupted all-weather protection even during power outages