Apple AirTag

Apple made the AirTag so simple that it's almost boring, and that is exactly why I want one. It's a white disc the size of a quarter that you drop in your bag, and then your phone can find it using every other iPhone around you as a relay. The whole Find My network runs silently in the background with no setup required from anyone. At $29, the price is low enough that you can buy 4 and not think about it.