A standard series of sizes referred to by numbers, in which the diameter of wire or thickness of sheet metal is generally produced and which is used in the manufacture of brass, bronze, copper, copper-base alloys and aluminum. These gauge numbers have a definite relationship to each other. In this system, the decimal thickness is reduced by 50% every six gauge numbers- while temper is expressed by the number of B&S gauge numbers as cold reduced in thickness from previous annealing. For each B&S gauge number in thickness reduction, where is assigned a hardness value of 1/4 hard.