The warehouse shelves are generally customized according to the area of the
warehouse, and generally no standard size. In addition to the size of the
warehouse, the size of the shelves will be different.
For example, the same size warehouse, because the cargo in the warehouse is
not the same, a standard tray placed 1.2*1, then the shelves will be customized
according to the tray. However, in another warehouse, a handle of 1.3*1.1 is
stored, and the size will change.