This Lochinvar gasket is a crucial component designed for use in various heating, ventilation, and air conditioning (HVAC) systems. It is specifically engineered to fit between the flue and heat exchanger (HEX) of models FTX725-850. The gasket serves as a sealant to prevent leaks and ensure optimal performance of the HVAC system. Made from high-quality, durable materials, it can withstand high temperatures and prolonged use without degrading or losing its sealing properties. Its precise design ensures a perfect fit for the specified models, contributing to the overall efficiency and longevity of the HVAC system.