8" DuraVent DVL Double-Wall Black 90-Degree Elbow 8DVL-E90 This 90 ° elbow offsets obstructions as needed. Elbows angles are adjustable. Use with DuraVent factory-built chimneys 430-alloy stainless inner wall aluminized steel outer wall 1" outer diameter Reduces clearances from 18" to 6" for walls Reduces clearances from 18" to 8" for ceilings Sturdy construction to ensure long-lasting durability Creates a tight secure connection in your venting system .016” stainless steel inner wall. .018” galvanized outer painted black.