6" DuraVent DuraTech Aluminum 7/12 - 12/12 Roof Flashing 6DT-F12DSA This 7/12 - 12/12 roof flashing is used with metal or tile roofs. 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 .016†430 stainless steel outer wall or .018†galvanized steel outer wall. .018†aluminized steel intermediate liner. .016†430 stainless steel inner liner. Insulated layers plus ventilated air space. Locks tightly with a precision twist-lock connection.