Volume Damper or balancing dampers are control dampers that regulate the flow of air but are not intended to be used in applications as a positive shut-off.  These dampers are with manual hand quadrants that can be locked in place (manual volume damper) or with motor actuator (motorized volume damper).  Made of Galvanized Iron, Aluminum or Stainless Steel.  Available in single blade or multi-blade system, square or round versions.  Can be with flanged type or non-flanged type.