Abstract: An insulated cooler for carrying perishables and cooling medium such as ice is improved to provide an extended period during which low temperatures are maintained. A sheet of flexible, synthetic insulation material is placed over the perishables and cooling medium. The sheet is pressed downwardly against the perishables and cooling medium, thus substantially conforming to the upper surface thereof. A dead space may be defined above the sheet and below the cover of the cooler. Preferably, the insulation material is air entrained polypropylene, which could be washed, is sufficiently flexible, and can be trimmed to fit the cooler. The insulation material is preferably folded into at least three thicknesses and trimmed to conform to either the footprint of the insulated cavity, or to an enlarged size, so that the outer edges of the material can be tucked down and about the perishables in the cooler.