Throttle Body Boot
A throttle body boot connects the intake pipes to the throttle body in Audi's 2.7T Engine. This is covered in detail in the list of 2.7T Commonm problems.
OEM Audi Throttle Body Boot for the 2.7T Engine: 
Aftermarket
Aftermarket Throttle Body Boot made by Samco, also for the 2.7T: 
