8" DuraVent DVL Telescoping 40" - 68" Pipe Length 8DVL-68TA This 40" - 68" pipe length is used for a two-piece installation from stove to ceiling support box or finishing collar. No cutting required. 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.