Maximum security box with string and button closure keeps contents secure, even if box is overturned. Up to 50% stronger than other string and button boxes to enable stacking without shelving. FastFold® quick and easy assembly. Reinforced, plastic handle makes it easy to pull a box out of a stack or off shelving. Box Type: Stackable File Storage; Box Style: FastFold® Quick & Easy Assembly; Strength: Heavy-Duty; File Size Format: Letter.