Shark Cordless Vacuum with Auto Empty System | BU3521UKForget about emptying for weeks at a time. Every time you finish cleaning, Shark Clean & Empty automatically deposits the dirt into a completely sealed base unit that holds dirt and debris for up to 30 days. No more manual emptying after every clean simply return the vacuum to the dock and let the hands free Auto Empty System empty the cordless vacuums dust cup into a large bagless base. Seals away dust & debris. Inside the base, fine dust particles