Blue Pure 121 Light Gray Washable Pre-Filter, Removes Pollen, Dust, Pet Dander and Other Airborne Pollutants, Lunar Rock, by Blueair

I actually bought this for a different unit, hoping that based on dimensions, it would work. It does! I love that I can pick other colors and that it helps keep the dog fur and bigger particles out of the filter. Only negative is I think I was sent the wrong color, otherwise the Lunar Rock color is insanely dark (super dark gray, almost black). Pretty sure I was sent the darker grayish color. This is likely due to Amazon making a mistake, not the company. Other than that, highly recommend.

I monitor and measure the air quality in my bedroom. I can see that these filters work very well. Only downside is the high cost every six months.

I love that I was just able to change the look of my air filter by switching from the blue to the gray fabric. It changes the look of that whole part of my room. I love it. This is one of the best parts of the Blue air filters.

See above. I chose the light gray, but other colors are available.

I have a few of these prefilters for my air purifiers, but something has changed with the quality. The older ones I have were thicker and never got any holes. All the new ones i buy get holes after first or second delicate wash. Disappointing and unacceptable. I should not have to be replacing these all the time.