Raven 6 Quart Back Pack Vacuum & Standard Tool Kit The decision was never easier. Sandia?s commitment to airflow efficiency has culminated in the Raven Series. All vacuums test to their optimum performance when new. The true test of performance comes as debris fills the vacuum bag. In older tubular backpack designs, the bag bulges and stretches when it fills, contacting the side wall and top of the vacuum motor, severely reducing airflow. The new Raven?s 3/4" per side increase in diameter and new bag support increase airflow and reduce motor heat, allowing an increase in motor warranty to 5 years! The Raven added 70 inches of sound deadening waffle foam materials to make the Raven the quietest vacuum in its category. The Raven clearly takes the Technological Edge in vacuum design and efficiency!