You can’t tell just by looking at it. There’s no visible difference between two identical pieces of sheet metal, a polished or grained the exact same way. That’s why you need a material test report (MTR) of the actual material to validate it as being 304 or 316 from us after shipment. We can assure our customers that the products ordered from SHS are constructed of the exact stainless steel material, as specified through MTR.