Depending on the type of key finder you're using, it can operate either using a Bluetooth or RF signal. Bluetooth devices can be paired with your phone and a specific app to determine the whereabouts of the key fob. This isn't quite like a GPS locator, however, as Bluetooth only has an effective range of about 30 feet. RF key fobs have a longer range, but can't be paired with your phone, but instead rely on a dedicated remote. While these won't give you a specific location on a map, they can still emit an audible or vibrating signal up to 100 feet. However, due to the necessity of the remote, RF key fobs are more well suited for in-home use.