I first purchased these almost a year ago when they were first released and I'm glad that I did. My son was visiting Boston from Wyoming, and the night he was flying back, his wallet fell out of his pocket while getting the Uber to the airport at 2am. When he let me know, I marked it as lost, assuming we probably wouldn't ever see it again. When you mark it lost, you can add your phone number and a brief message to whoever finds it. Sure enough, I was on my way to the office the next morning when I got a call from a lady who found it while walking her dog. My son's plane hadn't even arrived home yet. We texted back and forth and she was nice enough to mail it to me in Wyoming and I Venmoed her the cost and a reward. So they definitely work. Thank you for a great product.