The 0800 Collection is available in two frame models to be used with steel duct: a double flange screw gap mounting form (M1) or possibly a knock-in excess of tab form (M2). Both of those models feature a straightforward installation Lower-out template which makes the oval form openings more straightforward https://andyxpeth.blogdomago.com/35726715/heavy-duty-stainless-steel-damper-manufacturers-can-be-fun-for-anyone