Review on IOYIJOI Filter Replacement for Holmes Aer1 Series: Get 4 Filter Replacements + 8 Booster Pre Filters for HAPF300AH-U4R, HAP242-NUC by Bill Kodba

Tired of paying high prices for manufacturer replacements. They work great. I've noticed that many reviewers don't know what to do with the included activated carbon filters. When you replace the main filter and turn on the device, just wait a few seconds. Once the air has flowed through the main filter, simply place the activated carbon filter over the main filter and the airflow will hold it in place by itself. You get so many extra carbon filters on top of the main filters that I think the intent is to just throw them away when they get too dirty and put a clean one in their place. About half the life of the main filter.