BASS STRING SET D'Addario EXL230 Heavy Long Scale [55-110] (055 - 075 - 090 - 110). - D'Addario XL Nickel bass strings are world renowned as '' The Bassist's Choice '' whatever style you play. XL strings are wound with great precision with nickel plated steel onto a hexagonal shaped core, resulting in strings with a 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.