Only three millimeters thick and smaller than a business card, it can hold up to 10 credit cards and a good deal of cash in its nylon strap. And every time you remove a card, it'll send an alert to your phone to return it, which not only serves as a way to thwart theft, but also your inherent forgetfulness.
Already a few road sodas in and want to open a tab? Just boot up the complementary app and let it know. Then, after a certain amount of time has passed, it will send a helpful reminder that you haven't returned the card.