Buyers must prioritize magnetic properties such as Initial Permeability (μi), Saturation Flux Density (Bs), and Coercivity (Hc). For soft ferrites (MnZn or NiZn), the frequency range and core loss are critical. For hard ferrites (SrFe or BaFe), the Maximum Energy Product (BHmax) is the primary performance indicator. Additionally, ensure the particle size distribution (D50) and purity levels (e.g., Fe2O3 content >99%) align with your specific manufacturing process, whether it be injection molding or sintering.