Cheap, thin plastic but still sturdy, and reliable. My 60 card double sleeved decks fit snugly into these boxes. These boxes will not hold 75 or 100 card double sleeved decks, too small. They also arent going to protect your decks against something major like a wooden or more solid plastic construction would. For that expensive commander deck, go with something higher end, but for cheaper decks being carried here and there, these are really great.