For the B2B market, you must distinguish between Nickel-Plated Steel, Pure Nickel, and Stainless Steel. Nickel-plated steel is the industry standard for its balanced tone and magnetic response, making it suitable for mass-market retail. Pure nickel is preferred by vintage-style enthusiasts for a warmer tone, while stainless steel offers superior corrosion resistance and a brighter sound, ideal for players with high-acidity sweat or those in humid climates. Ensure the core is made of high-carbon hexagonal steel to prevent slippage of the wrap wire and ensure tuning stability.