BASS STRING SET Pack 2 sets of 4 strings for bass XL series Nickel Wound, Regular Light, Bright Round Wound (045-065-080-100). D'Addario XL Nickel bass strings are world renowned as '' The Bassist's Choice '' whatever style it plays. XL strings are wound with great precision with nickel plated steel onto a hexagonal shaped core, resulting in strings with distinctive, brilliant tone and excellent intonation. Nickel plated steel wire wound to the core is known for its distinctive bright tone and excellent tuning for all styles.