They're really more like card holders, but I looked up that term and found they've now been rebranded as "minimalist wallets." Hey, even minimalism can be commoditized and sold. All that is solid melts into air after all.
A lot fewer people regularly use business cards and a lot more people rarely use cash or need to carry a lot of cards with them given they can store info on their phone. I carry one made by Saddleback and it's perfect for me.
