The Airpura RpHB600 Replacement HEPA-Barrier filter is compatible with the C600 and T600 air purifiers. This specially-designed HEPA Barrier traps particles and dust after the carbon bed, and helps increase the efficiency of the other filters. Regularly replace the HEPA-Barrier filter in your C600 or T600 every 12 months for proper maintenance. This item includes both the filter frame and cloth.