Volume Damper
  Rectangular (Multi-blade and Single Blade Type) Model : DS-331 
    Round Type
   Flat Oval Type
COMPONENT CONSTRUCTION
Frame : 16 gauge, galvanized steel, mechanically joined
Blade :  1.6 mm. galvanized steel
Linkage : 1/8 inch rolled steel
Axles :  1/2″ diameter
Bearings :  Oil Impregnated