D'Addario was the first to use Phosphor Bronze in acoustic guitar strings back in 1974. Today, they are considered to be the standard in acoustic strings, thanks to its beautiful sonic balance and tonal warmth. Pioneering Phosphor Bronze acoustic guitar strings are precision wound with phosphor bronze wrap wire over a high-carbon steel core, providing tonal versatility suitable for all acoustic styles and musical genres. These 11-52 Custom Light gauge strings have slightly more volume and projection than Extra Light, while still being easy to play.