Types 1221-DOW and 1221-OW are "from wall" substantial functionality mix fireplace/smoke damper precisely suitable for applications in which the damper cannot be mounted throughout the aircraft from the wall or floor. They features Nailor’s distinctive inter-locking double skin airfoil blade style that eliminates combustible seals and delivers flame and smoke seal under hearth https://becketttlbpe.webbuzzfeed.com/37478997/the-fact-about-dampers-for-industrial-sector-that-no-one-is-suggesting