7" DuraVent DuraTech Double-Wall Finishing Collar with Adaptor 7DT-FC This finishing collar with adaptor fits into the female end of the chimney pipe to provide a decorative black finish. Use 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. Approved for most fuel types 430-alloy stainless steel inner wall 2" clearance to combustibles ThermalTech blanket insulation eliminates hot spots Twist-lock connections for strong secure fits Able to vent large fireplaces and building heating appliances Clean smooth exterior finish 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.