The fillable plastic block allows you to control the amount of weight ballast that you use with the system kit, meaning that in heavier winds you can enhance the durability of the system by simply filling it up the blocks with a variations of Water, Sand or Concrete. The fillable plastic bases are designed with an effective stacking system so that the bases can be easily stored and safely stacked in storage when not in use. It also comes with the solid crossbar top section offering increased visibility and durability of the kit and increased protection to the overhead electrical cables.