ShellyBLU Door/Window (the Device) is a Bluetooth sensor designed to detect the opening and closing of a door or a window. It can also measure the angle of a inclination of a door or a window that tilts and turns. In addition, it features a light sensor. Features � Long battery life � Door/window opening and closing detection � Door/window inclination angle measurement � Illumination measurement � Beacon mode � Encrypted mode Main applications � Residential � MDU (Multi Dwelling Units - apartments, condominiums, hotels, etc.) � Light commercial (small office buildings, small retail/restaurant/gas station, etc.) � Government/municipal � University/college The devices uses a 3V CR2032 battery (included)