Cost: $65 and up on Kickstarter
OS: iOS, Android
Recurring Fees: None
Boomerang is only available through their Kickstarter page at this time. It is not a GPS device. It uses Bluetooth, working similar to the My Buddy Tag . Boomerang will let you know when your kid leaves the designated zone or when they get wet. It lasts 200 hours (about three months of regular use) on one battery, which is replaceable like a watch battery. While it’s still in development, the final design promises to be comfortable, secure and rugged.