Abstract: A box formed of corrugated cardboard which is assembled in a reinforced manner so as to transport heavy objects such as books. An improved gripping hole is provided from an end wall extension twice folded over, resulting in a broader bearing surface. Disclosed are lid panels with a curved portion and a straight portion which interlock and prevent deformation. The bottom of the box is substantially reinforced by side wall extensions which are inserted through cutouts in end wall extensions and laid back to form substantially the entire inner bottom surface of the box.