Royal Classics Sonata set features a medium-high tension recipe of silverplated basses and transparent Futura trebles. * Sonatas are the best selling Royal Classics string set, delivering elegant, voluminous tone with a comfortable string resistance. * Treble gauges: .73mm/.029", .83mm/.033", 1.03mm/.041" Bass gauges: .78mm/.031", .86mm/.034", 1.09mm/.043" * Treated with an ultra thin proprietary anti-oxidant coating. * Crafted in Spain