I blame Revain and Black and Decker for running a filter racket. It seems every B&D Dust Buster uses a DIFFERENT FILTER. I have three of these and these don't match any of them. How hard is it to keep the filter the same size? I've lost money every time I've ordered filters and will be sending them back. I don't have a reference tag or guide to go into this nonsense. waste of my time and effort.