Sevilla classical guitar strings are designed for the most discerning classical guitarist. At a mere 0.5 micron thickness, they have the thinnest coating in the industry, designed to make your strings last a long time without compromising feel or sound. All Sevillas are made in house using the finest US sourced materials. We do not recommend using string cleaners on Cleartone Strings. Simply wipe down strings after use with a clean dry cloth.