The outside material is iron sheet(0.8mm), and the inside material is aluminium plate(0.5mm).Between the iron sheet and the aluminium thermal insulation(1.5cm). 13l Dimension:29.5*23.5*36cm Inner box:25.5*19.5*26.5cm Packing:35.5*28.5*40.5cm Gw/nw:4.5/3.5kgs 20'/40'/40h:700/1500/1600pcs