This is an aftermarket HEPA-level filter built as a compatible replacement for the Eureka HF9 filter. It is not a genuine Eureka part, but it is sized and rated to fit the same machines that use the HF9. HEPA-level filtration captures fine dust and particles down to a very small size, helping the vacuum maintain suction and exhaust air quality as it ages. Replace the filter periodically to keep the machine performing as designed.