One set of 3 EnviroCare Brand Washable replacement filters to fit Shark Rocket model numbers: 

HV300, HV310, HV320, HV305, HV301 & UV450

Filters are washable and should be cleaned frequently. Do NOT install damp or wet filters back into your machine. Damp or wet filters can cause mold and mildew problems and/or motor problems. 

Cleaning filters is important but they still should be replaced frequently.