HEPA Filter/ FL1000It is important to ensure the HEPA filter is replaced when needed in order to trap the maximum dirt and allergen particles in the air. When used correctly, the HEPA filter can trap particles as small as 3 microns in size. To apply, remove the Vacuum Exhaust Cap and insert the HEPA Filter, making sure the rubber lip is firmly set in the exhaust hole. HEPA filters can be used with all KleenJet models including HEPA filtration systems.