Modern Stacked Office Chairs (Set of 4)Ergonomic Back Design: Curved backrest conforms to natural spine shape for enhanced comfort and posture support Durable Steel Tripod Base: 11mm solid steel with arch structure ensures high stability and load capacity up to 180KG High Performance Materials: Injection molded polypropylene and fiberglass construction resists wear and maintains structural integrity Rigorous Quality Testing: Passed 108KG tensile test, 40KG rubber back cycle test, and