EnviroCare Replacement Pre Motor and HEPA Vacuum Filters for Dyson DC17 Machines Dyson DC17 Filter Kit Includes Washable Pre-Motor Filter (911236-01) and Post HEPA Filter (911235-01) By Envirocare #974 & #994 Replaces 994 974 911235-01 911236-01 DC17 Filter Kit DC17 Post HEPA Filter DC17 Pre Motor Filter F974 F994 Filter Models. Captures The Following: Mites, Pollen, Household Dust And Other Particles.