MFs quantify the demand for all material extractions (biomass, metal ores, non-metallic minerals and fossil energy ...), regardless of where it takes place worldwide

3 Pros:
•    It is helpful to include all globally involved material, of whatever type, in one sum
•    Allows cross-country comparisons
•    Allows comparisons across products and production technologies

3 Cons:
•    Sheer weight is a highly insufficient descriptor
•    Washing water and chemicals weigh the same 
•    Cyclic and non-cyclic usage is unrespected