Older B&D vacuums have filters with no holes in the bottom. These vacuum cleaners did not have a pre-filter. New vacuum cleaners come with a pre-filter. If you are upgrading an old vacuum cleaner, you will need perforated filters and a pre-filter. Look for this: Black & Decker 90558115 PREFILTER. You all work together. Images: 1. Pre-filter set to filter2. the pre-filter is not fully screwed into the grooves of the filter3. Pre-filter removed, cracks visible