Fender UltraCore Bullets 4250 nickel-plated steel electric guitar strings are designed for players who demand refined feel, defined clarity and dependable tuning stability. At the core of each string is Fender’s reinforced UltraCore high-carbon steel core wire, engineered for enhanced strength and precise pitch control under demanding playing conditions. Wrapped in premium roundwound nickel-plated steel and paired with Fender’s patented Bullets design for Stratocaster guitars, these strings deliver focused articulation, balanced sustain and consistent performance while maintaining long-lasting durability.