Gauges 10-13-17-30-42-52. Ernie Ball 2151 Hybrid Slinky Acoustic Guitar Strings are crafted from 92% copper, 7.7% tin, 0.3% phosphorus wire wrapped around tin-plated, hex-shaped steel core wire. Has a light orange, gold color and provides mellow, ringing sound, with excellent clarity. All Ernie Ball strings are precision manufactured to the highest standards and most exacting specs to assure consistency, optimum performance, and long life. Ernie Ball is the pioneer of rock and roll guitar strings. Jimmy Page, Eric Clapton, Steve Vai, and Slash are among the long list of Slinky players.