Vornado AQS 25/35 Replacement PreSorb Filter Works with the HEPA filter replacements for increased air filtration Presort replacement filter for Vornado AQS25 & AQS35 air cleaner Uses coconut carbon, the best absorbent available Helps extend life of cleaner's HEPA filter by trapping larger particles Eliminates many household and commercial odors Built to meet U.S. voltage requirements. Certified, safety-tested, and warrantied for use only in the U.S.