Cleartone Sevilla Classical High Tension w/Ball End Trebles: Nylon Basses: copper silver-plated wound, coated Made in USA Named after the famous city in Spain, Sevilla Classical Strings are designed for the most discerning classical guitarist. Sevilla Strings are classical guitar strings that feature Cleartone Strings Patented EMP Coating. At one micron, these strings treatment is the thinnest coating in the industry, designed to last a long time without compromising the feel and sound of traditional strings. Cleartone Treated Strings feature the finest material for the best sound. With longlife-coating. EMP Treatment (Cleartone-EMP – Enhanced Molecular Protection) is then applied to the strings to ensure longest tonal life without compromises.