Oreck's upright bagged vacuums incorporate a "dirty air system" in which dirt is pulled through a fan that breaks it into smaller particles that get sucked up into the vacuum. The smaller motor drives this fan, as well as the rollerbrush. Because these smaller motors (viable because of the direct suction design), sit closer to the floor they provide efficient suction and are able to spin the roller brush incredibly fast. So with Oreck's direct suction design you get a vacuum that's both powerful and lightweight.
Oreck's Saniseal® system is engineered to automatically seal shut and lock in the dirt when you are removing a full filter bag from the vacuum. Because the Saniseal is part of the cardboard collar of the disposable bag it seals the bag when the bag is removed from the bag dock. The dust and dirt that you've vacuumed up cannot escape. What's in the bag leaves your home for forever!