The Engel BP25 insulated cooler backpack is entirely welded while most of its counterparts are sewn. By welding all seams, warm air is kept out, dramatically increasing the life of the ice or ice packs inside. The welded seams ensure there will be no air or water leaks and will allow the soft-sided BP25 to keep beverages cold for 3.5 days, according to an independent review. The BP25 backpack with cooler boasts an outer shell composed of durable 840 denier fibers, which provide maximum strength and abrasion resistance. The exterior is laminated with a Thermal Plastic Urethane (TPU) film, adding another layer of strength and puncture resistance. The leakproof backpack cooler has 1-inch of closed-cell foam insulation, preventing air from passing through it and improving the thermal range of the cooler.
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