Freestanding plastic shelving units weigh less than metal shelving units and will not rust. They stand on a floor and provide multiple levels of storage for organizing and staging tools, supplies, and inventory. They make efficient use of vertical space in warehouses, stock rooms, and other storage areas without having to mount shelving to a wall. Stationary plastic shelving units are suitable for areas where they will not be moved often, and mobile plastic shelving units roll to allow for cleaning or repositioning.