NPS 8100 Series Poly Shell Stacking Chair, Black Features A One Piece, Injection Molded, Color-Impregnated, High-Density Polypropylene Seat/Back Shell And Frame Shields To Protect Against Snags And Pinching Anti-static Shell Frame Is Chrome Plated With 17-Gauge 7/8 Square Tubing Can Be Stacked 12 High With 6 Stack Bumpers On Each Chair To Protect Finish 3 Underseat Cross Braces For Added Stability And Durability 10 Year Warranty