D’Addario XS Phosphor Bronze 13-56 Medium Coated Acoustic Guitar Strings offer long-lasting tone and durability for all types of acoustic guitars. These strings feature a smooth XS coating over warm, balanced phosphor bronze, combined with a NY Steel core and Fusion Twist technology for enhanced break strength and tuning stability. Medium gauge 13-56 strings deliver maximum volume, projection, and tension, making them ideal for players who want a powerful, reliable sound.