Here’s the liner to use when converting existing chimneys to the DuraVent DirectVent Pro System. The 3" diameter is used with the DirectVent Pro Co-Linear Chimney Liner System. The 4" diameter is used with the DirectVent Pro Factory-Built and Masonry Chimney Conversion Kit.
Always check appliance manufacturer’s specifications for liner sizing requirements. Made of flexible, 2-ply .010" aluminum.