This little device can produce a 90 dB sound, which is louder than a typical landline phone ringing. Once within range, you can open the app and select the tag you want to start ringing. This really helps you find your keys quickly.
The advertised 200 foot connection seems like a massive exaggeration. In real-world tests, it would lose connection around 60 feet and wouldn't pick up the connection again until it was 20-30 feet away. This very short range isn't much help in finding your keys.