Secondary air pump vacuum line with high temp silicone ends. Dont spend $40.00 on buying this at the stealership, this is same one I use in my families 2000 323Ci, 2000 328I and 2002 330CI. If you have a check engine light on and your engine is throwing codes, it could be a simple vacuum leak. The original hose from BMW cracks and leaks over time. Installation takes less than 10 minutes.