Primary products represent the set of products that are associated with the 6-digit NAICS of an industry. These 10-digit products have classification codes whose first six digits match the 6-digit NAICS industry with which they are associated. These products can be viewed as being typical outputs of that industry. In cases where an output can be produced by more than one industry, these outputs will have separate product codes for each industry. An example would be steel sheets that can be produced by either a steel mill or a rolling mill.