From Fabspeed these are their high performance drop-in replacement filters for the factory air box.
- Fits 2006+ Mercedes-Benz C/CL/CLS/ML/S/SL 500 & 55 AMG
- BMC Part Number: 521/20
- Lifetime filter is washable and re-oilable
- Original equipment for the Ferrari Formula 1 Team and Ferrari GT race team, as well as Porsche Motorsports, Mercedes Benz F1 and GT race teams, and the AUDI Motorsports Team
- BMC Air Filters have a 98.5% filtering efficiency rating according to international standards for filtering (ISO 5011)
- Sold as a set of 2