Bankers Box LIBERTY Heavy-Duty Storage Boxes, FastFold, String and Button, Letter, Case of 12 (00011) Maximum security box with string & button closure keeps contents secure, even if box is overturned. Up to 50% stronger than other string & button boxes for stacking without Shelving. Fast fold quick and easy assembly. Reinforced, plastic handle makes it easy to pull a box out of a stack or off Shelving.