Developed and approved by our team of Master Luthiers, the Gibson Coated Phosphor Bronze 12-String Set is factory specification on all 12-String instruments built in the Gibson Acoustic facility in Bozeman, MT. These strings feature a high-carbon steel, hex-shaped core wrapped in phosphor bronze that is very thinly coated with a proprietary polymer. The result is unmatched durability that does not compromise vibrant tone like the rest. Discover the lush clarity and superior warmth that is suitable for any playing style.