Misplacing your keys, phone, purse and other valuable items can be a real hassle and very expensive. This bi-directional locator, the smallest smart key finder in the world, helps you track them down. Use your phone to find the tracker or vice versa! Attach to your keys, wallet or place in purse, gym bag... or wear it as a wristband. It is activated within approx. 100 feet/30 meters from your phone (depending on obstructions/signal barriers), beeping until found. Compatible with iOS 8.0 or later and Android 4.3 & up. Once you download the TrackerFind app on your phone, it can be used as a selfie remote or phone finder, making it ring even when on silent. The app includes a map that displays the last location where you left your item. Replaceable button cell battery installed/included.