I got the Boulder Deck 40+ CLEAR to store the cards that came with my copy of Street Fighter the Miniatures Board Game. Each character comes with a 41 deck of cards that I have put penny sleeves on and there's plenty of space for a full sleeve in the future. If you buy an Ultimate Guard Boulder Deck Case and use standard penny sleeves from Ultra Pro then the penny sleeves will not fit properly and can warp/curve your cards. I have been using a paper cutter to precisely snip the penny sleeves so the cards in the sleeves will fit with this product. The cases are well made sturdy plastic with the handy feature of being transparent small and conveniently putting your cards into the 2 halves of the case when playing with the cards.