The Spigen Slim Armor CS Case is one of the most popular cardholder cases for the Samsung Galaxy S9. It features a sleek and slim design that adds minimal bulk to your phone while providing excellent protection. The case has a hidden card slot on the back, which can securely hold up to two cards. It also has a sliding door mechanism that keeps your cards safe and prevents them from falling out. The case is made from a combination of TPU and polycarbonate materials, which provide great shock absorption and durability. It also has raised edges to protect the screen and camera from scratches. With its stylish design and practical cardholder feature, the Spigen Slim Armor CS Case is a top choice for Samsung Galaxy S9 users.