BMC 63 AMG Replacement Panel Air Filters Full Kit for 07-10 Mercedes CL FB521/20 Air Filter (FB521/20) by BMC Air Filter®. The panel / cylindrical air filter is commonly referred to as "replacement air filter". It is installed in the vehicle's original airbox to replace the OEM air filter. It is made of highly performing materials that allow an increased air flow combined with a more efficient filtration, guaranteeing containment of all impurities from as small as 7 microns (compared to OEM's 10 microns).
