These are four flap enclosures.  They are perfect for housing books, pamphlets, and loose pages.  They can be made either with or without a cover.  The cover provides protection for the four flap, and helps it to blend in with other items on your shelf.

Four flaps can also have decorative covers as shown below.  The football field is a pastepaper, and houses a souvenir program.

Click here to see images of drop spine boxes