6&#39;&#39; x 20&#39; DuraFlexSS 316 Stainless Steel Chimney Liner - 6DF316-20,Duravent" /> DuraFlex 316TiSS Chimney Liner is for use with pellet, non-condensing gas, wood burning, and oil appliances. 316Ti SS is designed for harsher conditions, for more resistance to corrosion, such as coal. Construction Material: 316Ti single-wall .005" stainless steel flexible liner. Listed to UL 1777 (MH14420) and ULC S635. Manufacturer's Limited Lifetime Warranty.