The Ernie Ball John Mayer Silver Slinky Signature Electric Guitar Strings are the result of a powerful collaboration between Ernie Ball and John Mayer. The string set offers players a unique, never before released string gauge combination. Each string was specially designed with specific core-to-wrap ratios to meet Mayer's preference and features reinforced plain strings for added tuning stability and durability. String gauges in this set are 10.5, 13.5, 17.5, 27, 37, and 47.