marerial: 1. out layer: HDPE, 2. middle layer: PU Foaming, 3. inner layer: food-grade HIPS. This is a combination set includes cooler ... layer:HIPS outer layer:HDPE middle insulation layer:PU Foaming Compound mode: TL750-1+TL-5+TL-20 Marerial: out layer: HDPE, middle layer: PU Foaming, inner layer ...