BreatheSmart 35i HEPA FilterOur filters arent like other filters. Theyre substantialin the best way. An Alen filter gives you the power to capture the toughest particles in your air. How? Our medical grade, H13 HEPA filters work in tandem with our incredibly powerful air purifier motor to capture pesky particles for a deeper, more thorough clean. With two filter options to choose from, you can optimize your Alen for your specific environment.