8" DuraVent DuraPlus Galvalume 19/12 - 24/12 Roof Flashing 8DP-F24 8" DuraPlus Galvalume 19/12 - 24/12 Roof Flashing is used to weather-proof the penetration of chimney pipe through the roof. Storm Collar required. Select roof flashing based on pitch of roof. Diameter: 8" Pitch: 19/12 - 24/12 Galvalume Storm Collar required .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.