Pratt PRA0118 100% Recycled Corrugated Cardboard Box, 20" Length x 20" Width x 4" Height, Kraft 100 percent recycled corrugated box for packing, shipping, and storing 32 ECT grade for standard stacking performance Flat square shape fits frames, books, or other flat items Made of single wall C flute corrugated fiberboard with standard kraft color Shipped flat to reduce shipping costs and storage space