DuraFlex SS Stainless Steel Chimney Liner - 4" x 20-ft. - 4DF316-20: A 4" inner diameter vent pipe is required for this unit. DuraFlex SS is a flexible masonry chimney liner that can be utilized with gas, wood pellet, oil, or wood appliances such as water heaters, boilers, furnaces, and fireplace inserts. It's more durable than other light liners because of the single wall 0.006" thickness. The most cost-effective liner for a straight chimney is DuraFlex SS. This item includes 20 feet of 4" liner. It should be used in conjunction with the DuraFlex Zero Clearance Insulation Sleeve to ensure compliance with the UL 1777 standard for brick chimneys and wood-burning appliances.

DuraFlex 20 Stainless Steel Chimney Liner 4-in. diameter Light-weight .006" metal thickness makes it stronger than other light liners Most economical liner for straight chimneys Manufacturers limited lifetime warranty