I have used these for about two years and they have worked great - especially when Air Canada couldn't find my luggage.  I have them in our backpacks and with our car keys.

On Black Friday I upgraded to the newest version.

Nothing wrong with these four.  They all have batteries (Tile lets you know when the battery is weak) with one just replaced a few days ago.

In original container.  These are the squarer version not the rounded ones.

Details and reviews:

Tile Mate (2018) - 4-pack : Amazon.ca: Tools & Home Improvement