#4401: 3.5″ Warm Air Duct Insulation (per foot)$7.00 #4401: 3.5" Warm Air Duct Insulation (per foot) quantity Add to cart Description Description Fits over #3410 ducting for additional insulation. Sold in up to 6′ pieces. Related products Add to cart #2460: Exhaust Vent (closeable duplex) $271.00 Add to cart #5430: Cold Air Inlet Vent $12.00 Add to cart #4414: 60/75 mm Warm Air Duct Adapter $27.00