The molded rectangular grille and square lattice grid is very similar, but the size can be selected is very small, only a thickness of 1 "(about 25.4mm) of the two models. 
 Such a grid, horizontal and vertical rib design, although the use of the trapezoidal cross section, but the section size and rib spacing are different. Although the transverse ribs to be narrower, but the vertical-intensive than many. So we just called the transverse ribs bearing ribs.