National Motor Freight Classification (NMFC) is the freight classification system that was created by the National Motor Freight Traffic Association (NMFTA) and is used for all interstate, intrastate, and foreign commerce movement of LTL cargo. NMFC codes provide standardized freight classes to determine the transportability of most of the countless different commodities that are shipped together in LTL shipments each year.
The National Motor Freight and Traffic Association has 18 freight classes numbered 50 to 500. The lower the freight class, the lower the cost of transporting that freight.
If you don't include an NMFC code on your BOL, it is very likely that your carrier will charge you a reclassification fee and charge you the cost of shipping the freight they determine your shipment is.