Duro-Shield multi-fit. Rain cap, bird guard, and spark arrestor. Hood is made from 18 gauge diamond embossed aluminum. Bracing and clamps are 1/8" x 1" extruded aluminum bar. 16 gauge aluminum expanded metal mesh. Nuts and bolts are stainless steel. Meets ASTM (American Society for Testing and Materials) D3034 and D2729 standards. Shipped KD (knocked down), easy-to-install. 13" x 13" outside tile size fits 11-1/2" x 11-1/2" to 13-1/2" x 13-1/2" outside tile dimension, 13" x 18" fits 11-1/2" x 17" to 13-1/2" x 18-1/4", 9" x 18" fits 7" x 17" to 9-1/2" x 18-1/4", 12" x 16" fits 11-1/2" x 15" to 12-1/2" x 16-1/2", 8" x 17" oval fits any near size, 13" x 17" oval fits any near size, 10-1/2" x 18" oval fits any near size.