1 Hoover C2401 Washable & Reusable HEPA Cartridge Filter Designed To Fit Hoover C2401 Commercial Shoulder Back Pack Vacuum & Royal Commercial Backpack model RY4001; Compare To Hoover FilteHoover Washable & Reusable HEPA Cartridge Filter Designed To Fit Hoover C2401 Commercial Shoulder Back Pack Vacuum & Royal Commercial Backpack model RY4001; Compare To Hoover Filter part # 2KE2110000 & 2-KE2110-000; Designed & Engineered By Crucial Vacuumr part # 2KE2110000; Designed & Engineered By Crucial Vacuum