These genuine dirt devil bags are the best value, and filter dust best with my Royal vacuum, for those who prefer to dispose of a bag outside the house rather than dump a 'catch-cup' indoors and put some of the dust you vacuumed back into the air. They are thin enough to allow the vacuum to fill the bag virtually full with my top fill vacuum and still allow plenty of suction for efficient vacuuming power. I have tried many bags from other makers with my Royal vacuum, but none work as well as these original type 'D' bags!