s a fire smoke detector alarm, alerts and warns people to stay far away from danger field when it detected smoke. Once triggered, the red LED will flash with a high volume alarm sound, louder than 85dB. Fits for areas like house, shop, hotel, restaurant, office building, school, bank, library, computer house, and storehouse, etc. With the special structure design and photoelectric signal processing technology, it features with dustproof, mothproof and anti outside light interference. Comes with an alarm test button. Press it after installation, if the buzzer beeps, then it works fine. The photoelectric sensor is designed for early detection from all directions. Easy to install and convenient to use. Specifications: Power Supply: 2 * 9V 6F22 Batteries (not included) Alarm Indication: Red LED Sound Level: ≥80dB Detecting Area: 20 square meters Operating Temperature: -10°C ~+50°C Operating Humidity: ≤95% RH Item Size: φ10.4*5.1cm/φ4.09*2.00in Item Weight: 77g/2.71oz Package Size: 10.9*10.9*5.7cm/4.29*4.29*2.24in Package Weight: 109g/3.84oz Package List: 1 * Smoke Detector Alarm 2 * Mounting Screws 1 * User Manual