The Lennox 51W11 Flush Mount Vent Kit is a venting accessory designed to provide a clean, secure connection for compatible Lennox heating equipment. It supports the proper routing of combustion air and exhaust gases through an exterior wall while maintaining a neat, low-profile installation. This kit is used with compatible Lennox gas furnaces and heating systems that require approved... https://www.partshnc.com/51w11-lennox-flush-mount-vent-kit