If you use the plastic bag for shopping. Please pay attention! I will show you how to use it again. 

Step 1：First of all, it must be dry. If it is wet, please dry it. Follow the direction (1)、(2), flatten the plastic bag and exclude the air from the plastic bag.

Step 2：Depend on picture 2, follow the direction (3) and fold it. Then fellow the direction (2), exclude the air from the plastic bag again. 

Step 3：Depend on picture 3, follow the direction (4) and fold it. 

      Moreover, if the plastic bag is too big, you can repeat step (2) and (3) and make the suitable size .

      Now you can repeatedly use the plastic bag when you go shopping, until it can't use.