Why PPE only uses 304 stainless steel and will never use 409 stainless for any PPE products.
304 stainless steel is the highest-quality stainless steel in commercial automotive use. 304 stainless steel is very tough and highly corrosion-resistant, with a 20% chromium and 10% nickel alloy content. 304 stainless steel is also nonmagnetic due to its low ferrous metal content, therefore not attracted to magnetic fields.
409 stainless steel is used in most stainless steel exhaust systems because of its significantly lower cost. With a lower chromium content (10-12%) and nickel alloy content at only .05% it is more likely to rust, especially in cold and wet climates. 409 stainless steel also contains a higher ferrous metal content causing it to be attracted to magnetic fields.