Those tiny sensors that attach to keychains or other items which allows you to wirelessly track things when they are lost have been around for quite some time.and#160; The 2 brands that get most of the attention are Tile and TrackR.and#160; On their face, they appear to be similar, but anyone looking for a slight edge should, look into TrackR over Tile.and#160; The TrackR's thinner sensors can do more and the user replaceable batteries aren't those special expensive batteries.and#160; An interesting feature of the TrackR devices is that you can also be used to figure out the location of your phone when you can't figure out where you left it.and#160; Both companies use Bluetooth with a range of roughly 150 feet of bidirectional signal.and#160; When you buy a large number of them, you can get the cost down to $10 to $15 a piece, making it affordable to track lots of items.and#160; Check out the most current options at: https://www.thetrackr.com