This filter set comes in of 4. H13 True HEPA filter is used in combination with Activated Carbon filter. High Efficiency: MA-25 replacement filter consists of a filtration system, including pre-filter, H13 True HEPA filter and Activated Carbon filter. Long-lasting and : It is recommended to replace the filter every 6 months or 2500 hours. H13 True HEPA filter can remove up to 99.97% of particles below 0.1 microns. : Suitable for MA 25 air purifier, can be used as MA-25 replacement filter. Color: As Shown Material: Activated Carbon Package Contents: 4 * HEPA filters Only the above package content, other products are not included. Note: Light reflection 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.