The box is from Stampin' Up! It's designed to keep and store wooden stamps neatly on a shelf. I am finding heaps of fun purposes for them. Here is the back.
The boxes have a plastic sleeve front and back so you can slip a piece of patterned paper in side ( like you do with a DVD case). You could keep rolls of ribbon, buttons and brads in them, birthday cards and any kind of card making kit with small pieces.
This box will fit 10 cards inside easily. I have included 10 cards and stamped envelopes in plastic sleeves.
The boxes are $11.95 for a pack of 4 (works out at about $3 each).
And you can get them in stackable half size cases too.