Wireless window door contact with solar cell and battery (service life 8 years) 75x25x12mm, glossy pure white. Fixing through adhesive. Smart home sensor Wireless window door contact with solar cell and 75x25x12mm battery. The window door contact FTKB provides itself with a solar cell from 100 lux daylight, otherwise several years with a button cell. When closing and opening, the relevant message frame is sent twice in quick succession. The current status message frame is sent cyclically approx. every 8 minutes. Fixing through adhesive. Dimensions of window door contact LxBxH: 75x25x12mm. Magnetic dimensions LxWxH: 37x10x6mm. If the power supply of the solar module is not sufficient, the electronics are powered for several years by an internal coin cell CR2032. To change the battery, you simply have to open the casing. This is also necessary to activate the battery supply by pulling out an insulating strip. The sensor learn message is sent upon pressing the learning button. When the le