D'Addario Pro-Arte Classical Guitar Strings The Pro-Arte series are a worldwide best-selling nylon string set for classical guitar. Combining high quality materials with the unparalleled manufacturing consistency of D'Addario, Pro-Arte strings provide every player with the balanced performance they are seeking. Detailed Design Nylon strings require a whole different level of quality inspection to assure that each set and each string is made with precision. With this in mind, each nylon treble within a Pro-Arte set is laser measured to calculate diameter and tension levels to deliver pure intonation and tonality every time. Core Elements The other unique aspect of the Pro-Arte construction is the use of a silverplated copper winding on a proprietary multi-filament nylon core to create the basses. The use of the multi-filament core allows the Pro-Arte basses to blend warmth and projection perfectly into one set.