Honeywell 50250-S True HEPA Air Purifier Captures up to 99.97% of microscopic allergens, 0.3 microns and larger, from the air that passes through the filters SurroundSeal Technology helps minimize air leaks, 3 air cleaning levels , Intelli-Check electronic filter indicator reminds you when to clean the HEPA filter and when to change the pre-filter Patented 360? degree air intake and discharge maximizes efficiency Most effective for Large to Extra Large Rooms, dimensions: 18.00 x 18.00 x 19.00 inches To ensure stated product performance, use only Certified Honeywell Replacement Filters