They are indeed Apple items! Similar to tiles as they use Bluetooth but with the much larger Iphone population they are more efficient at finding items, or so they say.
It seems a cheap way of checking that an item is not stolen or if it is, where it is now. They are really meant for luggage, wallets, handbags etc but are also useful for cars - if you forget where you have parked it can lead you there for example. Just thought someone might have used one on their boat.