This app beeps ,vibrates and flashes if your child or pet is 20 or 30 feet away from you so you don't potentially loose the child. It works by sensing the range to your bluetooth earbud that you can keep in your child possession (in the child pocket). Please note that for this to work the app should be launched and the bluetooth device should be on and paired with your phone. Recommend to make sure that your phone and earbuds are charged. Warning: This is only helping tool and not intended to replace continuos and vigilant physical body contact with your child.