Technical Properties: Plenum boxes are designed to operate with HEPA filters standardly. But they can be used without filters but with special suction and blowing vents according to the demand of the customer. They can be connected in two ways: connection from side or connection from bottom. Plenum boxes are proper for suspended ceilings and they can be easily mounted to the ceiling with suspending-holes on them. Flexible duct connection can be made from upper part or from side according to the customers' demand. Plenum boxes are dyed with white electrostatic oven based powder dyed.