Models 1221-DOW and 1221-OW are "away from wall" higher performance mixture fireplace/smoke damper especially suitable for applications where the damper can't be mounted inside the aircraft of your wall or floor. They characteristics Nailor’s unique inter-locking double skin airfoil blade style and design that eliminates combustible seals and gives flame and smoke seal https://heavy-duty-stainless-stee12233.bloggosite.com/44308033/the-smart-trick-of-heavy-duty-stainless-steel-damper-manufacturers-that-no-one-is-discussing