An organization called the National Motor Freight Traffic Association (NMFTA) publishes a list of freight class designations, codes, and subclasses for many frequently shipped items (https://classit.nmfta.org/). To view this list, you must pay a subscription fee. Learn more about freight classes from the experts at Koho for free on our freight classes pages.
Freight class 50 is the least expensive because it refers to the freight that is easiest to transport for the carriers.
NOI stands for Not Otherwise Indicated. This is used when a commodity does not have an NMFC code. In these cases, density is usually used to determine freight class.