Kair Rectangular Ducting 180mm X 90mm - Airbrick With Damper. This airbrick fits inside Kair Rectangular Plastic Flat Ducting 180mm x 90mm, and its part number is DUCVKC651. The backdraught shutter prevents unpleasant odours, noises, or draughts from flowing back through your duct. It has a depth of 60mm for the rear spigot and is designed for use with 180mm X 90mm ducting. This product is suitable for various applications including whole house ventilation, passive stack ventilation, air conditioning, HVAC, and Heat Recovery Systems. The maximum operating temperature is +60°C and the minimum is -15°C. The weight of the unit is 0.26 pounds.