Ernie Ball 2215 Skinny Top Heavy Bottom Slinky Electric Guitar Strings are a hybrid set for players who prefer thicker bottom strings for rhythm playing but still want the ability to solo on thinner strings. The wound strings are constructed from nickel-plated steel wire wound around a hex-shaped steel core, providing a bright and balanced tone. The plain strings are made of specially tempered, tin-plated, high-carbon steel for durability and consistent performance. These strings are renowned for their longevity and are trusted by many legendary guitarists, including Jimmy Page, Eric Clapton, Steve Vai, and Slash. The gauges included in this set are 10-13-17-30-42-52.