Features●Sensor Type:photoelectric●5 year battery life time●DC 9V battery operated (included)●Photoelectric chamber of early detection from all directions.●Loud>85db(A)alarm signal(3M)●Flash alarm indicator(red LED)●Low Battery signal●N.W.:≈124g (include battery)●Alarm Indication: Red LED & BuzzerInstallation method1. Choose the right installation placement.2. Drill 2 round holes with 5mm diameter on the ceiling. ( Distance between the two holes is 75-80 mm)3. Use the enclosed two expansion rubber and plugs into the holes.4. Install the mounting bracket of the smoke detector on the ceiling. by using the two screws enclosed.5. Install the smoke detector bttery to the mounting bracket. Note: Step 3 and 4 can be ignored if it is mounted on a wooden ceiling.Maintenance1. It is recommended to press the test button every week to check the smoke detector works correctly.2. To ensure the sensitivity of the product, clean the surface of the detector with soft brush every month.3. The smoke detector is with fault detection function. When the smoke sensor is short circuited or disconnected, the detector will automatically detect and send a fault signal. For example alarm will emit a beep between two flashes. When the battery voltage is too low, the detector will periodically sendFAQ1.How do I stop my smoke detector from beeping?If your smoke detector is beeping regularly, it could be because the batteries are running low.