Bi-directional ribbing system which includes four (4) full-height ribs in either direction and five (5) half-height ribs, thus providing strength while minimizing surface area contact.

• 双向罗纹系统，包括四（4）全在两个方向的高度肋骨和五（5）半高肋骨，从而提供了力量，同时尽量减少接触面积。