Buyers must prioritize the Magnetic Grade (e.g., N35, N42, N52), which determines the flux density and pulling force. For standard consumer applications, N35 is common, while industrial or high-end desktop toys may require N42 or higher. Additionally, verify the Dimensional Tolerance, typically ±0.05mm, to ensure the balls align perfectly in geometric shapes. The Coating Quality is critical; look for Triple Layer Coating (Ni-Cu-Ni) to prevent corrosion and chipping, which are common failure points in low-quality magnets.