Double-end, 1 1/2-side, double-bottom construction. Medium-duty for use with or without shelving. FastFold™ quick and easy assembly. Deep, locking lift-off lid stays in place for secure file storage. Rolled edges add strength and prevent paper cuts. Box Type: Stackable File Storage; Box Style: FastFold™ Quick & Easy Assembly; Strength: Medium-Duty; File Size Format: Letter.