Abstract: An economic stackable container of foldable corrugated material with improved strength for forming a stable stack of containers. Ventilation spaces are provided between stacked containers. The arrangement of panel is disclosed. An extension formed at the top at each corner projects into a notch formed at the bottom of a respective corner of the container above. The panels are particularly reinforced by folded panels at the corners. A separate reinforcing sheet is applied around the periphery of the panels of the main sheet. The sheets have their corrugations in the various panels oriented for strength.