The DAddario XT range sets a new standard for premium coated guitar strings. Each string is covered in a microscopic thin treatment, lasting three times longer than uncoated competitors. Material Made using a high carbon NY steel core and fusion twist ball end, XT strings are incredibly break resistant, hold seriously strong tuning stability and protect against corrosion. Phosphor Bronze is a 92% copper, 8% tin alloy with traces of phosphorous. These produce a naturally warm, smooth tone and work well for any type of playing technique. Coating XT strings are manufactured in DAddarios New York factory, known for its immaculate quality control and consistency. Not only will you have peace of mind theyll last you through gigs, hours of practice and recording sessions, but youll also notice the coating doesnt affect the dynamic tone or feel.