SPECIFIC and ad valorem rates of duty represent two distinct administrative aspects, and may also have very different effects upon both merchants and the community. In general, the merits of one are the demerits of the other, and their bearing on the formation of a tariff has already been indicated. The balance of advantage will determine which type shall be adopted. In the United Kingdom tariff many examples of each type are to be found both separately and in combination. Specific duties have the disadvantage that they cannot well be applied to highly specialized goods without much prior inquiry as to the precise borders of such class and rate, and a very complicated classification would arise. Ad valorem duties permit much wider limits and therefore a smaller number of classes in a tariff. From the administrative standpoint ad valorem duties are a satisfactory solution for that part of a general customs tariff embracing highly specialized goods.