This product is a battery operated photoelectric smoke alarm. It adopts unique structure design and stable photoelectric sensor technology, able to monitor and detect smoke particles in real time, especially detects visible particles sooner than ionization alarms. Once smoke particles or fire danger is detected, this alarm will chirp and the LED will flash rapidly to alert you and your family in time. Furthermore, this alarm has dustproof, mothproof and anti-light function to ensure its stability from design basis, suitability for early warning and protection of fires in houses, factories, shopping malls, hotels, office buildings, school buildings, banks, libraries and warehouses etc. indoor places.