They are rubber and for my first one I made the mistake of using this little key ring instead of a carabiner which splits one of the connection holes on the top of the AirTag case. As such, I recommend only attaching these AirTag cases with carabiners, which seems to work pretty well. They are a good buy and I plan to use them in my purse and travel bags but as they are made of rubber I wouldn't use or trust them outside of anything for more than a year.
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