Compatible with Air Purifier HEPA & Activated Carbon -PUR131 Replacement Filter Filter replacement kit includes one (1) HEPA Filter and one (1) Charcoal-based Activated Carbon Pre-filter for Air Purifier -PUR131, Part -PUR131-RF. Captures 99.97% of airborne particles and contaminants as small as 0.3 microns, including pet dander, mold spores, pollen, smoke, and dust. To replace the air filters in your -PUR131 air purifier, follow these steps: 1) With the air purifier off, unplug the unit and remove the back cover. 2) Remove the old air filters and dispose of them properly. 3) Unwrap the new filters. Place the Activated Carbon filter inside the housing first, ensuring the pull tabs face the opening. 4) Install the True HEPA filter into the housing; ensure the pull tabs face the opening. 5) Replace the back cover onto the housing. 6) Plug in and turn on the air purifier. Use a pen or pencil to press the black reset button located inside the vent on the side of the unit. The "Change Filter" indicator should turn off. Be sure to clean the dust sensor on the side of the air purifier using a clean cotton swab. When to Replace Filters: Air filters should be replaced every 6 months, depending on usage. Premium compatible HEPA filter replacement set for Air Purifier -PUR131 Color: Black + White Material: Plastic + Sponge Package Contents: 1 x HEPA Filter 1 x Activated Carbon Pre-Filter Only the items listed above are included; other products are not included. Note: Lighting and display settings may cause slight variations in the color of the item shown in the image compared to the actual product. Measurement may vary by +/- 1-3 cm.