6" & 8" DuraVent DuraTech Galvalume Adjustable Roof Support 6DT-ARS This adjustable roof support is designed to support the DuraTech Chimney and allows the chimney to pass through the roof and extend down the ceiling. Ideal for cathedral ceilings and free-standing appliance installations. Supports a maximum total chimney length of 45' above and 20' chimney below Roof Support. Adjustable to different roof pitches. 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.