Sporting a tin-plated hexagonal steel inner core string wrapped in an 80% copper/20% zinc brass alloy, the Ernie Ball 2010 Earthwood 80/20 Bronze Light Acoustic 12-String Guitar Strings are a double-sized portion of organic guitar tone. Ranging in gauge from .009 to .046, this pack brings easy playing to a 12-string setup that elicits a full sound with the option for easy strumming.