POLYMER COATED XTRA-LONG PLAY Polymer Coated is a New Age Solution to an Age Old Problem! All acoustic strings are susceptible to the elements. VINCI has developed a polymer shield that is bonded to these phosphor bronze alloys. This coating virtually eliminates tarnish, increases playability, and improves tone for 3 to 4 to even 5 times longer than regular guitar strings. So you're not constantly restringing your guitar. Item# 864 Light: .012 .016 .025 .032 .042 .053 866 Medium: .013 .017 .026 .035 .045 .057 Check us out at: www.vincistrings.com