4x6-5/8 Masonry Chimney Conversion Kit (Includes: Cap Adapter, 18" x 18" Flashing, Round Ceiling Support Wall Thimble Cover, and Retro Connector). Termination Cap and 4" flex Liner Are Sold Separately. For Use When You Have A Masonry Chimney And You Want To Convert It To A System That Can Be Used With A 4x6-5/8 Free Standing Direct Vent Gas Stove.