Fusion Matched is the trademarked proprietary method that combines the highest quality, 100% made in the USA wire & 100% USA workmanship to produce strings with exacting core to-wrap ratios & tolerances. 80/20 Bronze wire is made from 80% copper and 20% zinc. These strings have balanced highs and lows with a slight increase in mid-range. 21050 - Extra Light 10-14-20w-28-40-50