STOCK & QUALITY.
Stock; all of the materials/objects that are kept and waiting to be sold.
Quality; of how good the standards of the objects are.
Advantages; you could have a lot of good quality stock, not too much not too little.
Disadvantages; You could have too much stock, or not enough, and it may not be to the best quality.
Example; Food advertisements lead you to believe it's going to be perfect condition when in reality it's all soggy.