Bankers Box Liberty 11 Letter Size Storage Box, Carton of 12. Strong, durable storage boxes are designed for frequent access and maximum stackability. Maximum security box with string-and-button closure keeps your letter-size files secure, even if box is overturned. Reinforced plastic handle makes it easy to pull box off shelving. Heavy-duty storage boxes offer easy one-step, FastFold setup. Stacking weight is 750 lb.