BiKN is a simple piece of hardware that tethers your phone to anything you don’t want to lose: your keys, your wallet, your cat, even your kids. BiKN comes with an iPhone 4/4S case and two tags (additional tags are $49.99 a pair), which you can attach to just about anything. A free iPhone app lets you communicate with the tags in Leash, Page, or Find mode. In Leash mode, the tag “pings” audibly when it gets far enough away from the iPhone. Page makes the tag beep wherever it is, so you can locate it by sound. Find mode tells you how far away from your tag you are, and which direction it’s in. And if you misplace your phone but have a tag handy, you can press a button to page your phone.