If you don't want to keep it in your regular wallet, get something really tiny like the Magpul micro wallet that holds 1-3 cards and will disappear in any pocket.
Too thick and expensive. The point is to be as small as possible, but the ridge had relatively thick side panels (like 2-3 credit cards) that make it thicker than it needs to be. I'd rather get something like this Magpul Wallet that's BARELY thicker than the cards inside the wallet. This is very similar and I carried one for several months and loved it. Just my two cents.
Magpul DAKA micro wallet. Link