When sourcing steel bathroom accessories, the material grade is the most critical factor for corrosion resistance. You should prioritize Stainless Steel 304 (SUS304) for standard high-quality projects, as it contains at least 18% chromium and 8% nickel, providing excellent resistance to humid bathroom environments. For luxury or coastal projects where salt air is a factor, Stainless Steel 316 is the superior choice due to its molybdenum content, which prevents pitting. Avoid '200 series' stainless steel for long-term use, as it is prone to rusting within months in high-moisture areas.