must be limited a polyurethane insulation provides one such suitable design choice other materials will obviously suggest themselves to those skilled in the art the base 16 comprises ridges 56 upon which the items or commodities 58 are placed these ridges 56 allow for circulation of the coolant gas which is carbon dioxide in the preferred embodiment thereby providing for better heat transfer the inner shell 28 of each of the side walls 18 and 20 illustrated in fig1 and the rear wall 22 comprise corrugations not shown so that the items 58 are not placed directly against the side walls 18 and 20 or the rear wall 22 thereby allowing for the free circulation of carbon dioxide gas between the walls 18 20 and 22 and the items 58 the items 58 occupy the first portion 60 of the insulated container 12 although the items 58 can entirely fill the first portion 60 the best results are achieved when there is a space between the items 58 and the pressurized coolant compartment 34 thereby allowing for effective heat transfer from the gaseous carbon dioxide contained within the first portion 60 of the insulated container 12 to the pressurized coolant compartment 34 the pressurized coolant compartment 34 is mounted in the upper rear portion of the insulated container 12 as is stated previously fig2 illustrates a cross sectional view of the pressurized coolant compartment 34 accordingly only the front wall 44 the rear wall 46 the top frame 36 and the base 48 are shown all four of the walls 40 42 44 and.