DESC: Ideal for rooms up to 155 square feet. Surround Seal filter technology helps assure virtually all of the air circulated through the air cleaner passes through the HEPA filter. Enviracaire 50100 Features and Benefits: 99.97% true HEPA filter. Recommended for a 11&#39 x 14&#39 small to medium room. Intelli-Check feature electronically monitors HEPA and pre-filter usage. Filter change indicator lights. Patented 360 degree air intake and discharge for effective air cleaning power.