The Authority in LIFE SAFETY DAMPERS Pottorff Provides the Perfect Solution for Any Condition! Our Newest Release For Corrosive and High Humidity Environments ... STAINLESS STEEL UL Class 1 Leakage Rated Airfoil Blade Fire/Smoke Damper Our FSD-151-SS features 304 stainless steel airfoil blades and is perfect for mildly corrosive environments or areas of high humidity. The airfoil design offers excellent air performance. Approved for system velocities up to 2,000 fpm and system pressures of 4" w.g. at 350° F. www.pottorff.comhttp://www.pottorff.com