· Compatible: Exclusively designed for MSA3/MSA3S Air Purifier with Membrane Solutions, to maintain its peak performance (4 Pack)· Dimensions: MSA3 HEPA filter replacement dimensions are 15.62 x 11.49 x 1.18. For best performance, recommended filter replacements once every 6-8 months. (depending on the environmental air quality)· 3-in-1 True HEPA Filter: MSA3 Filter features a 3-stage filtration design: Pre-Filter Captures Hair, Pet Dander, and Fiber; TRUE HEPA Filter Captures Smoke, Dust; Activated Carbon Filter Quickly captures and neutralizes Bad Smells, Pet Odor and VOC to freshen the air quality.(New Upgraded with the structure and content of activated carbon and the odor removal effect is greatly improved)· Filtration Performance: MSA3 Air Purifier uses True HEPA PP electrostatic electret melt-blown filter. Filters out 99.97% of particles as small as 0.3 microns and air pollution PM 2.5 (particulate matter). Helps to relieve common allergies like sneezing, coughing, and irritated eyes· Customer Happiness: Our responsive customer service team is fully committed to ensuring you have the best experience possible! If you have any questions or concerns, please contact us and we will answer ASAP!