Instead of the usual hexagonal core, the Fender® Classic Core strings feature a round core that serves as the foundation for a sound and feel typically found only in well-played strings. Right after stringing, you get a round, deep tone with smooth highs and a flexible string that makes even extreme bends enjoyable. Pure Nickel Bullet Ends. Gauges: .009, .011, .016, .024, .032, .042.