HQRP Washable Filter fits Eureka Optima 431BX, 431F, 437AZ, 431DX, 431F, 437AZ Lightweight Vacuums Coaster HQRP&reg; Filter plus HQRP&reg; Coaster; This filter is HEPA filtration class H12 and retains 99.97% of particles down to 0.3 micron. HQRP filters are washable and reusable! 100% Compatible with Original filter; 2 weeks DOA replacement warranty!