the score line 43 and the short panel 39 along the score line 37 the free end of the folded tab is caused to enter the rectangular aperture 23 the tapered design allows it to be easily pushed through past the hinged keeper 35 and once fully inserted through the wall 19a of the tray the natural resiliency of the corrugated board causes the flanking sections 47 to spring back to their generally planar arrangement and locks the two walls together at the corner in mutually perpendicular orientation the outward return of the flanking sections 47 plus the keeper 35 assures that the corner lock cannot be inadvertently disengaged the other three corners of the tray 11 are easily interlocked in the same manner and the tray is then free standing and ready to be filled preferably the empty tray 11 is loaded on an empty pallet 13 and the products 51 are then loaded into the body of the tray filling the region between the four upstanding walls 19 the depending tabs 27 fit outside the edge of the pallet 13 as depicted in fig1 the tray 11 is particularly suitable for shipping products 51 which are close in shape to that of a rectangular parallelpiped for example the molded hard rubber casing of an automobile battery in the illustrated arrangement sixteen such battery casings 51 are loaded into the open top tray 11 in four rows of four each when the first tray is filled a second set up tray is located atop the filled bottom tray and it fits snugly into place because the depending tabs 27 frictionally engage the outer upper edges of the battery cases 51 therebelow as can.