HEPA Filter - as long as 5 years in normal use. Pre-filters - can be vacuumed from the exterior of the unit and should be changed every 3 months. HI-C carbon weave (optional) should be changed every 4-6 months depending on use. Pressure seal on the filter chamber lets all unfiltered air pass through without leakage. True 100 square foot 3in. deep folded HEPA filter traps 99.97% of particles as small as 0.3 microns. Optional HI-C carbon weave absorbs airborne chemicals, noxious gases and odors and can be changed every 4-6 months. Approximate treatment area is 2000 sq. ft.. Filter chamber sealed with felt gaskets. All metal housing ensures no plastic vapors are emitted. Virtually silent. Variable speed motor. Unimpeded airflow. Certified by the Environmental Technology Laboratory. Particle removal: 100 sq. ft. true HEPA, 3 in. deep, 10 pleats per in., pleats warm rolled with separators. Free Air Flow: 560 cubic feet per minute free flow, delivers 440 cfm with filters. Pre-filter: 570 sq. in. and 1 in. deep. Housing: Powder cost steel. Voltage Options: 115 or 220 Volts. Watts: 120 on high 40 on low. Noise: 28.1 db on low 62.3 db on high. Normal room sound is 25.1 db. 15 in. L x 15 in. W x 23 in. H (45 lbs.).