Selecting the correct material is critical for performance and safety. For slingshot or recreational use, Carbon Steel balls are the most cost-effective and provide high impact. For industrial bearings or high-precision machinery, Chrome Steel (GCR15) is preferred due to its superior hardness and wear resistance. If the product will be used in humid or corrosive environments, always specify Stainless Steel (304 or 316) to prevent rust. For non-lethal training or lightweight applications, Glass or Plastic (POM/Nylon) balls are suitable alternatives.