These numbers refer to the grade of stainless steel that's used to make this product. Type 304 stainless steel includes nickel, which offers superior corrosion resistance, while type 430 is made without nickel. Type 304 stainless steel is a great choice for use in wet or humid environments where rust and corrosion are a concern. Meanwhile, type 430 stainless steel is a budget-friendly option for use in dry settings.