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Master Flow

Model # F6IFD4X300

Internet # 100396934

Store SKU # 394317

4 in. x 25 ft. Insulated Flexible Duct R6 Silver Jacket

This item has been discontinued.
The Home Depot no longer carries this specific product.

$24.25 /each
  • R6 fiberglass insulation for greater insulating power
  • Duct can be cut to length as needed


Model # F6IFD4X300

Internet # 100396934

Store SKU # 394317

Store SO SKU # 755578

The Master Flow 4 in. x 25 ft. Insulated Flexible Duct R6 Silver Jacket is used in standard Heating and Air Conditioning (HVAC) systems and some venting applications. The duct has R6 insulation which contains 33% more insulation than the standard R4.2 product. This additional insulation provides greater thermal efficiency to save energy. The product is also covered in a heavy duty, silver jacket for durability. The duct is ETL listed, meeting the UL181 standard.

  • Flexible duct is convenient for use in multiple applications including heating & A/C systems and some venting
  • Oversized core to connect quickly and easily to standard sheet metal fitting
  • Galvanized core wire for greater corrosion resistance vs. non-galvanized wire
  • Insulated duct features a maximum temperature rating of 200 degrees Fahrenheit
  • Always install per instructions and seal using approved mastic or sealant (or approved tape)

Info & Guides

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Product Depth (in.) 
Product Diameter (in.) 
4 in 
Product Height (in.) 
Product Length (in.) 
300 in 
Product Width (in.) 
Silver Jacket 
Insulator material 
Maximum air flow (CFM) 
R Value 
Warranty / Certifications
Certifications and Listings 
2-UL Recognized,ETL Listed 


Rated 4.7 out of 5 by 27 reviewers.
Rated 5.0 out of 5.0 by Great Product and Excellent Value I bought this to use on a new bath ventilation fan. The ducting for the previous fan not insulated. The builder simply buried it under the sprayed insulation. I looked on the HD website and was amazed that this insulated ducting was a much better value then plain ducting. I only used about half the ducting so I have more for when I do the other bath fan. This duct is easy to work with and appears to be high quality. April 30, 2015
Rated 2.0 out of 5.0 by Check codes Check your local building dept and fan specifics. Our fan can move 80 cfm of air but this 4" duct can only handle 30 cfm. Needed to upsize to get best results. July 3, 2015
Rated 5.0 out of 5.0 by Exhaust It was easy to install the hose unit from the fan into the attic to exhaust the fumes in the bathroom. June 1, 2015
Rated 5.0 out of 5.0 by Good for bathroom vent fans I bought this after seeing a like-product used on This Old House to create a roof vent for bathroom fans. It works great and is easy to use/cut. This duct is compressed inside the box when you buy it, so be ready for it to continually "ooze" out of the box when you first open it. I only wish the Home Depot site had worked better, because it said the product was not carried in my local store, when in fact, it was. I happened to go down the ducting aisle a week after I bought this online and paid for shipping, and there were plenty of boxes of the ducting available in-store. May 28, 2011
Rated 5.0 out of 5.0 by good deal This 25' insulated duct was really a cheaper buy than uninsulated ducts, especially for the length as I could not find 25' uninsulated. And I needed every bit of that 25 feet. December 10, 2013
Rated 4.0 out of 5.0 by Easy, clean, strong, effective Replaced non-insulated bathroom flex-ducts with this stuff. It comes compressed in a box about 3-ft long which is real handy in tight spaces. The outside silver-jacket and inner flex duct materials were both a lot stronger and tear-risistant than I expected. It does take a few minutes and/or gentle massaging to reach full length, but this wasn't a problem. Highly recommend this material for similar applications, though be sure to get ALUMINUM or plastic couplers, not galvanized! Also, since the material is so strong, you'll have a hard time w/ any joints that aren't slightly undersized, the duct does NOT stretch larger (a good thing). January 13, 2015
Rated 5.0 out of 5.0 by Very good flex duct. Very easy to work with. The outer cover is pretty tough. I had to wedge and pull it through some tight spots but it didn't tear or rip anywhere. March 29, 2015
Rated 5.0 out of 5.0 by What you need for bathroom exhaust fans! If you are going to install a bathroom exhaust fan, or already have one, then this is what you need for properly venting it up and out of your roof. The insulation helps reduce condensation inside the vent duct in wintertime. In this box, you will probably get much more than you actually need, so it's a good value for the price. June 22, 2010
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