This filter set is a 4-Pack. H13 TRUE HEPA is combined with Activated Carbon 3-in-1 Filter.HIGH-EFFICIENCY: for Medify MA-25 replacement filter are made of 3-in-1 filtration systems including Pre-Filter, H13 True HEPA Filter, and Activated Carbon Filter.LONG-LASTING: It is recommended to change filters every 6 months or 2,500 hours.H13 True HEPA filter removes up to 99.97% of particles as small as 0.1 Micrometre.PERFECT FIT: Compatible for Medify MA 25 Air Purifier and can be used as MA-25 Replacement Filters.Color: black + whiteMaterial: Plastic + FiberPackage Contents:4 x HEPA FilterOnly the above package content, other products are not included.Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.