Round NRD " Back Draught Damper "
The Non Return damper is unique in that when air flows out of it gravity is the only source by which the backdraft damper closes and prevents contaminated air to filter back through.
This product has no valid combination.
The Non Return damper is unique in that when air flows out of it gravity is the only source by which the backdraft damper closes and prevents contaminated air to filter back through.
