Cold-rolled Steel MaterialLoad-bearing stability to withstand both small or large heavy duty PC tower. | Breathable Heat HolesDiamond-shaped heat holes provide breathable heat dissipation while the tower case is running, extending the life of the CPU. | Universal Wheel with Brake LockEach set has four universal wheels, two of them with brake fixed latch, the installation is recommended to be placed in the same front and rear. | Expandable Width AdjustmentAdjustable to the width of heavy duty PC tower for flexibility. |