2.2.2 If you are installing more than one hub, please turn off the power of all
hubs first. Then you can get another hub and place it above the previous one
on the working surface, as shown in Figure 2-7. Finally, put the stacking kit in
the middle of two sides and click into the stacking hole in the plastic housing.
Check if all hubs are tightly fastened by the stacking kits and proceed to next
Figure 2-7 Unplug the power,and stack two hubs together
Figure 2-6 Lay hub on stable desktop