DREW HEPA Replacement Filter - PURE 3+This Replacement filter is not compatible for DREW PURE 3 Air Purifier What is HEPA? HEPA stands for High Efficiency Particulate Air. A mechanical air lter that works by forcing air through a ne mesh that traps harmful particles such as pollen, pet dander, dust mites, and tobacco smoke. Are all HEPA filters the same? No, not all HEPA lters are the same. There are signicant differences in the HEPA lters being made by many air purier brands. Depending