DuraVent 3"-8" Inner Diameter DuraFlex Mortar Sleeve

Size: 3"

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

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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.


A Flexible Solution For Any Installation

Having a choice when making a decision is important. DuraVent offers the installer a range of products to make the right decision for the right situation. There are four different DuraFlex liners and a complete selection of DuraFlex universal components. No matter which flexes is right for the situation, there's a DuraVent component to complete the venting system



  • Use to protect DuraFlex when passing length through a masonry wall.


DuraFlex SW smooth wall 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 Dimension
    3DFS-MS 3" I.D x 6" Length
    4DFS-MS 4" I.D x 6" Length
    5DFS-MS 5" I.D x 6" Length
    55DFS-MS 5.5" I.D x 6" Length
    6DFS-MS 6" I.D x 6" Length
    7DFS-MS 7" I.D x 6" Length
    8DFS-MS 8" I.D x 6" Length
    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