Freestanding wire shelving units have openings that allow air to pass through the shelving for ventilation and let water flow through the shelving if fire sprinklers are activated. Items on the shelving can be seen through it, and dirt and dust fall through the shelving to help keep it clean. The shelving units stand on a floor and offer multiple levels of storage for organizing and staging tools, supplies, and inventory. They make efficient use of vertical space in supply rooms, stock rooms, and other storage areas without having to mount shelving to a wall. Stationary wire shelving units are suitable for areas where they will not be moved often, and mobile wire shelving units roll to allow for cleaning or repositioning. Wire bin shelving units have bins for separating and organizing loose items. Top-track wire shelving systems allow an aisle to be created between any two shelving units in the system as needed instead of having to leave an aisle space next to every shelving unit.