Slim carbon fiber / aluminum cardholder with RFID protection.
Those little chips on your cards can be scanned with a simple RFID reader or even a phone. The card holder has two aluminum plates that block the RFID chip preventing them from being scanned.
The RFID blocking isn't the reason I bought mine initially. I bought mine because I hate bulky & heavy wallets. These are sleek, lightweight, and just plain better than a folding wallet.
The cards slide in and out easily and cash is held in place by the money clip on one side. If you don't want the money clip simply unscrew the panel and it can be removed.