The heat preservation package method of the heat preservation lunch box is as follows:

1. Fold the thermal insulation bag and bag bottom into an edge with the length of 13cm.

2. Fold a 2.5cm triple hem at the mouth of the bag, and then fix it with suture.

3. Finally, insert the insulated lunch box and tie it tightly with a rope. The above is the insulation package method of the insulation lunch box.