I was thinking last night (could be dangerous) about my plans to modify Gunny into a smoker and thought I may be trying to hard to perserve the original 1944 military oven parts especially in relation to the exhaust damper. Bbally had figured I needed 10 sq. inches of exhaust for this thing. Drawing on experience in other areas (I certainly have little in pit building) I came up with this. This is a all metal 4" blast gate for dust collection systems. My concern was the galvanized blade. SS is available but very expensive. This one can be bought for 12 bucks. It is already flanged on both sides for pipe. A 4" has the equivalant of 12.556 sq. inches of opening. As to the galv. the entire unit is outside the cook chamber of a smoker being designed to run 375 F max well below the 600 F gassing temp often talked about. The housing is aluminum and can be taken apart for cleaning with screws. These screws in the housing would seem to make it possible to run a high heat sealing compound around its parameter and bolt to the smoker. What do ya all think?