D'Addario EXL115BT Balanced Tension Medium Electric Guitar Strings (2-Pack) Two packs of Medium guitar strings Mathematically optimized string gauge combinations Nickel wound EXL115BT gauges range from 11-50 The EXL115BT Medium Electric Guitar Strings are part of the D'Addario Balanced Tension Series that are comprised of mathematically optimized string gauge combinations, resulting in greater control and playing comfort