FEATURES * Compatible with APH260 Air Purifier and APH320 Smart WiFi Air Purifier only. * True HEPA Technology: Fine pre-filter, true HEPA filter, and activated carbon filter work together to capture harmful pollutants in indoor air. * Best Choice for Allergies: It removes 99.97% airborne particles as small as 0.3-micron, such as dust, pollen, bacteria, mold spores, pet dander, smokes, and VOCs. * Replacement Alert: When the PM2.5 light turns RED and keeps flashing, this is a reminder to check and change the filter, which is supposed to be every 6-8 months depending on its condition. To reset the replacement alert, press the FAN and TIMER button simultaneously and hold for 3 seconds. * Friendly Reminders: Please ensure to power off before operation. Remember to close the front shell properly after the replacement. Otherwise, it will fail to process power out of safety concerns. WHEN? * Replacing the air filter every 6-8 months is recommended for optimal use (or according to your air filter status). * It is time to replace the air filter when the following signals appear: Increased noise, Decreased airflow, Clogged filters, Presence of odors from the unit. HOW? * Unplug the air purifier and remove the front shell. * Remove the old filter and then unwrap the new air filter. * Install the new filter and make sure the pull-tab on the filter is facing outward and put the front shell back. * Press and hold the FAN and TIMER button simultaneously for 3 seconds to reset the unit. Then the replacement reminder will be off. Frequently Asked Questions * What's a True HEPA Filter? HEPA stands for High-Efficiency Particulate Air. HEPA filters, originally designed by the U.S. Army to remove radioactive materials from the air, are the most effective way to remove pollen, dust, and other indoor particle pollutants. A True HEPA filter can remove 99.97% of airborne particles 0.3 microns or larger-- that's 166 times smaller than a human hair. Sometimes, you may see some filters named HEPA-like or HEPA-style, or HEPA-type. Unlike true HEPA filters, these filters cannot actually remove 99.97% of bacteria down to 0.3 microns in diameter. * What’s the difference between HEPA and Medical Grade HEPA Filter? Generally speaking, the higher the HEPA filter grade, the better the purification effect. True HEPA filters usually range from H10-H12. And the highest grade of HEPA filter is H13-H14, which is considered to be medical grade.