When the WALN alarm detects smoke or high temperatures, the alarms connected to the same hub beep to alert you. One hub can control 16 Meross devices (including sensors, detectors, thermostat valves) simultaneously. In addition to smoke detection, it can also detect overheating. If the temperature is too high (54 - 70 degrees), a beep will sound to remind you. There is also a low battery warning. The maximum alarm sound level is 85 dB. When high temperatures or dense smoke are detected, the Meross app or the Apple Home app will be notified immediately. Even if you are not at home, you can receive alarm information in a timely manner. The smoke detector is tested according to EN 14604, EN 61000, EN 50130 and certified by Intertek and SGS. Set triggers to control other Meross devices in the Meross app, for example, to turn on the Meross bulb in the hallway when the smoke detector goes off. More usage methods are waiting to be unlocked by you. Compatible with Apple HomeKit (iOS 13 or higher) and SmartThings. Device control is supported through the Meross app and Apple Home (Apple Watch, Apple TV, HomePod). Android users can use the Meross app on Android 6.0 or higher.