Stainless has chromium added. Iron is still the main element. Different stainless steels have various other elements added, like molybdenum. There’s a wide range of SS for various purposes depending on their formability, weldability, corrosion resistance, heat treatment or precipitation hardened. Some are mildly magnetic (400 series), others not (300 series). Big range of cost too. Not sure which one they used. There’s also a finishing process called passivation that should be used to reduce the likelihood of corrosion.