The deck boxes fit all my sleeved cards just right. I love that they are clear, so I can see their contents quickly. No need to clutter things up with labels.
My particular use case was to reorganize everything for the Mage Knight Ultimate Edition board game. Each of the seven characters has their own box with starter decks, tokens, and figure. Most of the remaining cards fit in the other three boxes.
For this example, I needed just one more box to contain all the cards. Since this product comes in a pack of ten, I just found a box I had lying around to hold the tile description and extra wound cards.
For anyone who cares, these deck boxes, my extra box, two 3600-size tackle boxes (holding all remaining tokens, enemy figures, mana, and dice), the map tile holder cut from the original insert, fame and round boards, and instructions all easily fit in the Ultimate box with the original insert removed.