Top flaps interlock to make files easily accessible yet keep contents clean and secure. This storage box is recommended for letter size files; No tape or glue needed. One piece cartons folds together in seconds; Double layered bottom provides extra strength; Manufactured from 200#/ECT-32 corrugated; Cartons feature a write on area on two sides for labeling with content information; Sold in cases of 12. Sold in a quantity of 12 per case.