Marine Grade Stainless Steel is the ultimate weatherproofing stainless steel. Marine Grade Stainless Steel is similar to Grade 304, except it contains 2% to 3% of Molybdenum. This white metallic element is used to toughen steel, and increase corrosion resistance & rust proofing of the stainless steel. It has one of the highest melting points of all pure elements. You can guarantee Marine Grade 316 Stainless Steel is weather resistant to all outside elements, especially if you live near the coast.