The Engel High-Performance Backpack Cooler Bag features a rugged, tear-resistant 500-denier polyester diamond ripstop outer shell with a waterproof TPE coating for easy cleaning. The inside features a radiant barrier liner of reflective foil, in addition to a 1-inch thick layer of closed-cell foam insulation. While the insulation effectively minimizes heat transfer to maintain cold inner temperatures, the radiant barrier liner reflects the sun's long-wave heat radiation to further enhance the Engel High-Performance Backpack Cooler Bag's cold-keeping capabilities. Under typical conditions, the Backpack Cooler will hold ice for up to three days.

NOTE: The 2017 or later model of the backpack coolers do not include the removable liner and the old liner does not fit. This is due to a new TPU material interior that no longer requires the liner.