The box is constructed in the form of a rectangular container with high sides and rolled edges. A rectangular lid, which also has rolled edges, fits over the walls of the box, and is attached to it by means of two rolled hinges positioned along one long side. The box was originally intended to be hung from two perforated tabs soldered to the base of a short side. It may be fastened closed by means of a large latch soldered to the center of a long side.

A rectangular slot is cut into the cover of the box, to permit slips of paper to be inserted. The box has been painted overall with black enamel. On the lid is painted, in what appears to be darkened yellow paint, the face of a roaring (actually, a smiling) lion, whose jaws surround the rectangular slot. On the lid are painted instructions for its use: "Gentlemen / are requested / to deposit in the / Lion's Mouth / The / Titles of such Books / As they may wish to have / Imported."

Used by the Library Company during the years when Franklin was associated with it