When selecting sprockets, you must prioritize material grade, typically C45 steel, stainless steel (304/316), or alloy steel for high-torque applications. Ensure the pitch (P) and number of teeth (Z) align perfectly with your chain specifications. For high-wear environments, specify induction hardened teeth (HRC 40-50) to extend service life. Additionally, verify the bore type (pilot bore, finished bore, or taper bush) and surface treatments like black oxide, zinc plating, or chrome plating to prevent corrosion.