See the link elsewhere for Chipolo. It's killer. I've used it so many times now to find my lost wallet that I'd gladly pay twice the cost.

I was recently existing an airplane, and realized I didn't have my wallet in my pocket. Folks were packing up behind me, and I was getting pressure from my family to start existing down the aisle. I wasn't sure if the wallet was somewhere in my carryon or on the floor of the plane. I was scrambling checking pockets of various carry on bags, etc. The I remembered I could ping it. Within seconds, I could hear the chirp and very quickly found it.

Highly recommend!