Keep tabs on your phone and other essential items - with the PROTAG Duet Bluetooth Tracker Kit, including two black Duet tracker units. Each Duet uses Bluetooth 4.0 LE technology to connect wirelessly with your smartphone. Using the free iOS/Android PROTAG app, you can configure your phone to ring when the Duet's button is pressed. Simply attach one of the Duets to any item and ring the Duet using the app to find your item when it's missing. You can also set up the Duet to ring itself and your phone whenever they're out of range so you don't leave your phone behind. The app is able to manage up to 10 Duets at once.