Warm, lush, and full sounding Acoustic strings along with outstanding sustain are what characterize Cleartone’s award-winning Phosphor Bronze. Ultra-low carbon stainless steel hex core covered by American made Premium Phosphor Bronze. All painstakingly wound on our custom computer-controlled in house winding machines. Additionally, all 6 strings receive our twice patented Cleartone treatment which increases lifespan, volume output, and sustain. Patent numbers 7531730 & 9502008. Look them up. Our founder, Phil Everly of the Everly Brothers, said to only use the very best of everything in our string recipes. He wanted people to forget about everything in the world and to fall in love with playing guitar. Try a set today and see how good your guitar can really sound.