Greenheck has added two new models of stainless steel backdraft dampers to its backdraft damper line. The SSNM-10 Series is a horizontally-mounted back- draft damper designed to allow vertical airflow up and prevent reverse airflow. The SSNM-30 Series is a vertically-mounted backdraft damper designed to allow horizontal airflow and pre- vent reverse airflow. Opened by air pressure differential and closed by gravity, both the SSNM-10 and SSNM-30 Series dampers are rated for pressure differential up to 2 in. wg. and velocities up to 2,500 fpm. Three types of frame construction are available: no flange, flange on discharge, and flange on intake.