Intelligent sensor for doors and windows, Sonoff DW2 - RF 433MHz, has been designed to enhance the security of your home against break-ins. The sensor sends a notification to your phone every time a door or window is opened or closed, ensuring your safety and providing peace of mind. You will receive alerts on your phone if an unwanted guest attempts to open a window or door in your home. With ultra-efficient battery performance, the low power consumption allows for a battery life of up to two years.