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. Light Gauge: .012 .016 .024 .032 .042 .053 - .012 .016 .010 .014 .020 .030