Designed to provide your fine guitar with enhanced protection. Martin Marquis Silked 80/20 strings have an added soft silk wrap on the ball ends preventing wear and tear on the bridge. The silk wrap adds a layer of protection enhancing corrosion resistance and providing reliable tuning stability. Manufactured with 80% copper and 20% zinc these acoustic guitar strings yield a bright and ringing tone. These Acoustic SP strings include gauge 13-17-26-35-45-56. Features Set of 6 acoustic guitar strings Medium gauge 13-56 Metal wrap wire composition of 80 copper and 20 zinc Soft silk wrap added to ball ends Thread wrapping for enhanced corrosion resistance Specifications Gauges: 13-17-26-35-45-56 Tension: 193.0