Manufactured from non-combustible rock wool. It does not sustain vermin and will not encourage growth of fungi, mould or bacteria and is suitable for continuous operating temperatures of up to 500 degrees centigrade. You must use the foil tape for all joints. Pipe thickness is 25mm (1 inch) and lengths are 1000mm (39 inches). Comes in three diameters for the following liner sizes 140mm (to suit 125mm ( 5 inch )), 169mm ( to suit 150mm ( 6 inch )) and 219mm ( to suit 200mm ( 8 inch )). The 219mm diameter can easily be trimmed to fit 175mm (7 inch) chimney liner. (Not suitable for class 2 flexible liner).