8" DuraVent DuraTech Double-Wall Finishing Collar with Adaptor 8DT-FC This new integrated collar with adaptor fits into the female end of the chimney pipe to provide a decorative black finish. Use this on chimney pipe that is suspended with the roof support system or on pipe that is passing through a wall thimble. Provides proper connection to DVL or DuraBlack. No other adaptor is needed. 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 10â€-24†diameter pipes feature an .027†430 stainless steel inner wall and an outer wall of .029†galvalume or .027†430 stainless steel. A Refractory insulation is encased between walls. Only stainless pipes use the stainless end rings. Regular galvalume pipe uses galvalume end rings.