Genuine Audi HVAC Heater Hose lower (TT Quattro) - 8J0121063: Genuine Audi HVAC Heater Hose lower (TT Quattro) - 8J0121063 is a direct replacement for the original equipment manufacturer (OEM) part. This hose is designed to maintain the correct temperature and pressure of the coolant in the engine. It is made of high quality materials and is resistant to corrosion and abrasion. It is designed to fit the Audi TT Quattro model.