During the last event, Apple announced AirTag, a locator that uses the Find My network to find your keys, for example. AirTags use Bluetooth to easily get back your items that you have attached the tracker to.
In addition to Bluetooth, the trackers also have support for the ultra-wideband. That technology is in the iPhone 11 and 12 phones. The high frequency at which they work enables the AirTags to determine the location very accurately.
AirTag have IP67 water and dust resistance, Siri support, and over a year of battery life. The battery is also user-replaceable. AirTag are on sale from April 30 for € 35 or € 119 for a 4-pack.