National Motor Freight Classification (NMFC) is a freight classification system created by the National Motor Freight Traffic Association (NMFTA) and used for interstate, intrastate, and foreign commerce shipping of LTL cargo. NMFC freight codes provide standardized freight classes to determine the ease of transport of many of the huge variety of different commodities being shipped together in LTL shipments every year.
If the couch you are shipping has not been assembled yet and you are shipping various components that you can use freight class 250. If you are shipping a complete product then you should use freight class 175.
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.