Rack Supported/Shelving Supported – When Storage Rack is the storage medium of choice because of product size or bulk, a catwalk can be added to provide manual access to upper beam levels. This is a popular method for order picking situations which more than doubles the available SKU’s in a minimum floor space. Carton flow and Pallet Flow can be combined to maximize the utilization. If Shelving is the storage medium, it is possible to use the shelving to support the upper levels. The upper level can have a full mat floor to provide open space for packing tables, quality control or bulk storage. If additional shelving is required it can be an extension of the lower level and the decking material is then only required in the aisles as a catwalk.