Subclasses for
HSN stands for Harmonized System of Nomenclature. It is a system for classifying commodities created by the World Customs organization. U.S. LTL shipping, however, uses NMFC classifications instead.
Freight class 50 is the least expensive because it refers to the freight that is easiest to transport for the carriers.
Some items, such as car transmissions, have a specific class no matter how heavy or big they are. This is called a fixed class. Items can be assigned a fixed class if the value and transportability very rarely change.