Made from two separate strips of 316 stainless steel this 5" 316 flexible flue is the best on the market. It has an extended guarantee compared to other liners. This is due to the unique way that the liner is made. Most other liners use one strip of steel and fold it to create the inner and outer layer. It’s this folding that weakens the steel. As Dura Flue is made from two strips of steel this weakening doesn’t happen meaning it’s a strong more reliable flexible flue liner. You’ll require a 6 inch flue liner if you wish to burn coal, you can only use a 5 inch liner with a Defra Approved Wood Burning Stove.