Eureka pre motor foam filter replacement. Sometimes this filter is black but this is an original Eureka filter part. Designed to fit Eureka 8800 and Eureka 8850 series upright vacuums. Replacement filter # 77583-333N and # 77583.
The Eureka Boss Capture model 8803BVZ is an example of a 8800 series vacuum that uses the PMF1 filter.