BMC (WA250-500) Automotive Air Filter Complete Wash Kit BMC Filters are constructed using a process called "Full Moulding" developed by the BMC F1 R&D team; Detergent and Oil wash kit BMC air filters are designed and produced to ensure a higher air flow than OEM air filters The filtering material is composed of a special cotton gauze soaked with low-viscosity oil to give you the best air permeability BMC Air Filters are washable and reusable, perfect for high performance applications