D'Addario EJ41 was the pioneer in using Phosphor Bronze for acoustic guitar strings in 1974. Today, Phosphor Bronze is renowned worldwide and has become the standard for acoustic strings due to its exceptional sonic balance and warm tone. D'Addario's Phosphor Bronze acoustic guitar strings are meticulously wound with a phosphor bronze wrap wire over a high-carbon steel core, offering a wide tonal range suitable for all types of acoustic music. The 09-45 Extra Light 12-String set is D'Addario's most lightweight option for 12-string acoustic guitars, ensuring easy playability while still providing sufficient tone and projection for various playing contexts.