Buddy Tag (RRP$59.99) is a modern child safety wristband. It helps preventing lost child and accidental drowning. My Buddy Tag uses Bluetooth and is not a GPS tracker.
It features an Out of Range Alert to help prevent lost child, Water Safety Alert to help prevent accidental drowning, Panic Alarm for your child to alert you in a threatening situation; and Personal ID to help reunite a lost child with the parents.
It comes with Free Download App compatible with Iphone 4s & newer; Samsung Galaxy S3, S4, S5, Note2, Note3 with Android 4.3 or newer. BuddyTag is also compatible with the 4th Generation iPad, iPad Air, iPad Air2, iPad Mini, and the 5th Generation iPod Touch.
This sort of thing can be OK with your keys, but useless for kids, pets or anything else that moves.
For keys, your phone remembers the last seen location (you don't want it alarming every time you lose BT connection),
so you can go back there when lost, and wander around attempting to restore connection so the keytag can beep at you.
(it knows where the phone GPS was when it went out of range, so are the keys at home, in car, office, etc)
I can't see bluetooth working from the bottom of a pool. Maybe it released a floating emergency beacon when wet?