Wireless button tracker with battery (lifespan 5-8 years). 55x44mm, 15mm high. Weighs only 20 grams. Smart home sensor. The wireless button tracker FTTB has a blue push button with which the normal button telegram is sent. After opening the housing (reach into the joint and pull apart), the tracker can be switched on with a slide switch in the w position. The sensor then sends a presence telegram every 60 seconds. An internal 3V CR2032 battery provides power for several years.