Direct replacement for the OE idler & tensioner pulley on the legendary BMW S65 V8 found in E90 / E92 M3
The original SKF Bearings are retained for perfect long-term reliability, however you can just replace the pulleys rather the n the entire tensioner assemblies that are all that's available via BMW. Whilst thus is an aftermarket product, the quality and construction is exactly the same as OE, but at a fraction of the price.
The original pulley are known the wear out and seize. It is good preventative maintenance to replace these before they fail. Normally you will be able to audibly detect a failing pulley before it seizes .
Please note these are supplied with some bolts that will need to be removed and replaced with the original ones you remove from your car for best results.