I first heard of these about two years ago. They seemed like a brilliant idea, but getting hold of them was a rather laborious process. The other day I noticed the major precious metal exchanges were carrying them. So I snagged 40 bills worth. I'll almost certainly be adding to my collection in the near future. Highly fractional 24k gold you can carry in a wallet? Yes please.
I'm also stacking generic silver rounds of course.
https://goldback.com/