The DuraVent Direct Vent Pro Masonry Conversion Kit allows you to utilize an existing masonry chimney to vent a gas or propane direct vent stove. The conversion allows you to utilize the chimney to provide the combustion air. A 4" flexible chimney liner must be installed for the exhaust vent. The kit comes with a Cap Adapter, 18" x 18" Top Plate, Retro Connector, 4" x 35' Aluminum Flexible Liner, 4" x 6.625" High Wind Direct Vent Cap and Wall Thimble Cover Plate. The Retro Adapter will connect the 4" x 6.625" vent pipe to a 4" flexible liner. The Cap Adapter and Top Plate seal off the existing flue while allowing the chimney to gain the combustion air and supporting the rain cap.