Royal Classics KSM520 Kindersaiten Nylon Guitar Strings, Scientifically Calibrated for 52-57 CM Scale Lengths Royal Classics Kindersaiten series -- the world's finest fractional sized strings--are scientifically calibrated for shorter scale length guitars. Through scientific gauging, the Kindersaiten KSM520 set ensures proper tuning and superb tonality for most 1/2 to 3/4 sized guitars. Treble gauges: .65mm/.026", .75mm/.030", .91mm/.040" Bass gauges: .73mm/.029", .84mm/.033", 1.05mm/.041" Treated with an ultra thin proprietary anti-oxidant coating. Crafted in Spain by and for serious guitarists.