Heavy duty, triple-end, double-side construction stacks up stronger and withstands frequent handling. FastFold? quick and easy assembly. Reinforced tear-resistant hand holes make box comfortable to carry. Deep, locking lift-off lid stays in place for secure file storage. Smooth rolled edges add strength and prevent paper cuts. Box Type: Fast Fold?; Material(s): Paper; Strength: Heavy-Duty; File Size Format: Letter/Legal.