DuraVent 25' Flex Pipe Length DuraFlex 304 Stainless Steel Basic Kit

Size: 3"

Estimated Arrival: Between and . (To All Contiguous States)

✔ Same-Day Order Processing
✔ Free Returns
✔ No Restocking Fees
✔ Financing Options Available

Text or call 888-992-1556, start live chat, or email with any questions. Our team is available to serve you 8:00 AM - 11:59 PM ET, 7 days a week.



DuraVent is the premier company in the venting industry. With a broad range of engineered venting products, DuraVent has earned its reputation as the industry leader by offering innovative, safe, and professional products for the HVAC and Hearth markets.

DuraFlex 304 and 316 are lighter, more economical liners. Excellent when there are minimal offsets in the chimney. DuraFlex 304SS and 316SS are intended for wood burning, non-condensing gas, and oil-fired appliances. Where greater corrosion resistance is desired, such as in coal-fired appliances, DuraFlex 316 is recommended. DuraFlex 304SS and 316SS are listed as UL 1777 and ULC S635.

Customize The Flex You Need

All DuraFlex is available for orders requiring custom lengths (minimum 10' length). DuraFlex Pro and DuraFlex SW also offer 9"-12" diameters when ordered in custom lengths. (minimum 10' length). Use Ventinox components for all 9"-12" flex systems.



  • Kit flex lengths are available in 15’, 20’, 25’, 30’, and 35’.
  • Kit includes DuraFlex SS Top Plate w/welded Storm Collar, DuraFlex SS Removable Vertical Cap, DuraFlex SS Connector, and DuraFlex 304 length.


DuraFlex SS Top Plate With Welded Storm Collar
Used to seal the top of masonry chimney and support flex. Flex is secured to the storm collar with a fast connect band.
DuraFlex SS Removable Vertical Cap
Use to terminate a relining system. Attach to storm collar with fast connect band.
DuraFlex SS Connector
Use to connect DuraFlex SS length to an appliance, rigid length, or flex length.
DuraFlex SS 304 Length
Use with wood-pellet, non-condensing gas, wood-burning, and oil appliances.



DuraFlex 304 flexible relining for a masonry chimney. Use with gas, wood pellet, oil, or wood appliances. Applications include fireplace inserts, furnaces, boilers, and water heaters.



    Model Size Flex Length
    3DF304-25K 3" I.D 25 ft.
    4DF304-25K 4" I.D 25 ft.
    5DF304-25K 5" I.D 25 ft.
    55DF304-25K 5.5" I.D 25 ft.
    6DF304-25K 6" I.D 25 ft.
    7DF304-25K 7" I.D 25 ft.
    8DF304-25K 8" I.D 25 ft.
    Materials 304 Stainless Steel
    Construction Single-Wall
    Clearance 0” clearance for gas, oil, and pellet applications.
    Clearance 1” clearance to masonry for wood-burning
    Listings Listed to UL 1777 and ULC S635 (MH45609).
    Warranty Limited-lifetime warranty




    Warning: This product can expose you to Chromium, which is known in the state of California to cause cancer, congenital disabilities, or other reproductive harm. For more information, see CA Prop 65 Warning