In addition to the established arithmetic speed scale, ASA PH2.5-1960 also introduced logarithmic ASA grades (100 ASA = 5° ASA), where a difference of 1° ASA represented a full exposure stop and therefore the doubling of a film speed. For some while, ASA grades were also printed on film boxes, and they saw life in the form of the APEX speed value S v (without degree symbol) as well.