First you pair your Woolet with a mobile app. Since this, both of them will stay connected and measure the distance from each other. Thanks to Bluetooth 4.0 their contact is constant and lightning fast. When the distance gets too big your phone will notify you about it and the Woolet itself will make a loud sound. If you don’t know where you left the wallet, companion app comes equipped with a radar that shows the direction where to look . The battery is rechargeable and invisible, just like the PCB.