When sourcing pool stairs, the material is the most critical factor due to constant exposure to water and chemicals. You should prioritize AISI 304 or AISI 316 stainless steel. While 304 is standard, AISI 316 is highly recommended for saltwater pools or coastal environments because of its superior resistance to chloride corrosion. Ensure the tube thickness is at least 1.0mm to 1.2mm to prevent bending under heavy loads, and verify that the surface has a high-quality mirror polish or electropolished finish to minimize oxidation.