ROSLAU Piano Wire - Imported from Germany. Piano Wire is the "Blue Chip" of the steel industry. Because of its exacting requirements, only the finest grade steel of precise chemical analysis is used in it manufacture. To help assure beauty of tone, it must be exceedingly uniform in thickness and roundness. Tolerances are held to .0003". This wire is the finest available. Measured by the American Standard Music Gauge. Diameter: .041