The Lochinvar & A.O. Smith 100287143 Natural Gas Venturi with Gasket is a replacement component designed for compatible gas-fired boilers and water heaters. It regulates the flow of natural gas and helps create the proper air-fuel mixture required for efficient combustion. The venturi uses airflow to draw and mix gas before it enters the burner, supporting consistent flame operation. ... https://www.partshnc.com/100287143-lochinvar-a-o-smith-natural-gas-venturi-w-gasket