When evaluating magnetic shafts, you must prioritize Magnetic Flux Density (measured in Gauss or Tesla) to ensure it meets your torque or sensor requirements. The material grade of the magnet (e.g., N35 to N52 for Neodymium or Y30 for Ferrite) determines the strength-to-size ratio. Additionally, check the shaft material, typically SUS304 or SUS316 stainless steel, for corrosion resistance and mechanical strength. Dimensional tolerances should be strictly controlled, often within ±0.01mm, to ensure seamless integration into high-speed rotating assemblies.