What are the features of the square bottom valve bag? As follows: Reasonable mechanical structure: In the fall and drop test, the parts of the square bottom valve bag are in a state of equal strength, the gravity is evenly dispersed around, and there is no stress concentration phenomenon, which is more reasonable from the aspect of structural design. Experiments have proved that the firmness of square bottom valve bags made of different materials is 1 to 3 times higher than that of sewn bottom bags.