Two-Way Bluetooth Tracker Beagle is a small Bluetooth tracking device that helps you locate and remember your most important items. Never leave home without your wallet or keys again! Attach the Beagle tracker to a personal item like your keys. Then pair the Beagle app to your phone. Use your phone to track your keys. It can even alert you in advance when you may have forgotten your keys, purse, wallet, etc. Replaceable cell battery. 35mm x 35mm x 6mm. 1.37" L x 1.37" W x 0.23" H