Formulated of a tough, durable, and thicker gauged polyester plastic. Fasten system bolts directly to the area wall with a slide bolt assembly, making ventilation possible. Improves basement insulation. Keeps out snow, rain, and debris. Comes with brackets. Circular, 40" L. x 18-1/2" W. x 9-1/2" H., may be used with area wall Model No. RR3716-12 (SKU 101035), RR3716-18 (SKU 101044), RR3716-24 (SKU 101053), 75204-12 (SKU 100145), 75208-18 (SKU 100161), and 75210-24 (SKU 100439). Backed with a 5 year warranty.