This package contains 3 Netatmo Smart Smoke Detectors that alert you via the app on your smart device in case of smoke detection. You can hang the detectors throughout your home, allowing for quicker identification of fires. Connect the smoke detectors to your Wi-Fi, and you will always be aware of any dangers in your home or office. With a sound level of 85 dB, you will be immediately notified. The included battery lasts up to 10 years. When the battery is running low, the detector signals this with an audible alert. This way, you will know right away that you need to replace the battery and will never be caught off guard by unpleasant surprises.