Iris damper is galvanized steel constructed with EPDM rings. It is an ideal air flow regulator and measuring device for circular ducts. It provides a perfect accordance between the diameter indication on the handle and the opening of the valve. It provides 100% free area when in fully open position. Standard opening size are 4”,6”,8”, 10”,12”,14”,16”,18”,20”, or it can be manufactured according to customer’s needs.