▶Compatible for BLUEAIR Blue Pure 311i Max /F3MAX Air Purifier, NOT Compatible with Blue Pure 311i+ Max or 311 Auto. ▶H13 Grade True HEPA Filter, and High Efficiency Activated Carbon Filter ▶H13 Grade HEPA Filter 99.7% of airborne particles down to 0.3 microns in size,High-Efficiency Activated Carbon, filter All sorts of smells and smoke ▶Please replace regularly to keep your machine fresh, Replace every 6-12 months depending on the usage and environment ▶Easy to replace, can be installed without the use of any tools, if any problems with the process, please contact us NOT Compatible with Blue Pure 311i+ Max or 311 Auto. ▶Compatible for BLUEAIR Blue Pure 311i Max /F3MAX Air Purifier