The $29 AirTag ($99 for a pack of four) is a tiny metal tracker that you can attach to a keychain, drop in a bag, or snap onto your luggage to keep track of those items. AirTag works by using a Bluetooth signal to tap into a network of about a billion Apple devices in the world, like iPhones and Macs, that also broadcast a Bluetooth signal. If you lose something with an AirTag attached to it, you’ll get a notification with the location when someone with an iPhone or Mac comes within Bluetooth range of it. It’ll also show anyone who finds the item a custom message and phone number, which you enter when you report it lost. This is the AirTag. It’s a quarter-sized tracker. There’s a replaceable CR2032 battery, the sort of coin batteries that you might find in a wristwatch, that should last about a year. Truly, it’s best for recovering items that you lost or maybe hanging around the house somewhere.