I used and stored this for one day. You can store cards and other items inside, and customize it freely, making it sparkly and cute. I am selling it because I bought another cover. A protective sheet is also included as a bonus. The following is quoted from the product screen: - Acrylic stands and credit cards can be inserted. - There's enough space for a single credit card to move around inside. - It fits three cards, so it seems to accommodate items up to about 3mm thick. - I was able to use it with my front door key card, so - It might also be compatible with transportation IC cards. - You can arrange acrylic stands, purikura (photo stickers), photos, etc., to create your own original smartphone case. - Anti-sticking processing on the inside. Clear type, transparent, smartphone case, wavy, easy to grip, non-slip, soft type, flexible, "oshi-katsu" (supporting your favorite idol/character) iFace Look in Clear