Generally, it is a food container made of double-layer plastic or stainless steel plus vacuum layer or heat insulation layer. The top is covered and sealed tightly. The vacuum layer or heat insulation layer can delay the heat dissipation of food inside, thus achieving the purpose of heat insulation. The insulated lunch box is developed from the thermos bottle, and the insulation principle is the same as that of the thermos bottle. There are three ways to spread heat: radiation, convection and transmission. The silver liner in the heat preservation barrel can reflect heat radiation, and the vacuum layer or heat insulation layer of the cup can block heat transfer. Taifugao authentic stainless steel braised pot insulated lunch box porridge barrel insulated with pot.