With a tin-plated hexagon-shaped core steel string wrapped in an 80% copper/20% tin bronze alloy, the Ernie Ball 2012 Earthwood 80/20 12-String Medium Acoustic Guitar Strings offer some of the richest tone in a 12-string model. Ranging in gauge from .011 to .052, the medium weight allows for an even richer sound well-balanced between the demand of heavier strings and playability of lighter ones.