Royal Classics RM60 Guitarra Romantica Nylon Guitar Strings, Custom Calibrated for 19th Century Instruments RM60's were designed to maximize the tone of early instruments (Staufer, Lacte, Panormo, etc.) built with a shorter scale length than modern classical guitars. Sweet and balanced, Guitarra Romantica strings faithfully project the sound and charm of 19th century guitars and modern interpretations thereof. Treated with an ultra thin proprietary anti-oxidant coating. Crafted in Spain by and for serious guitarists.