This Washable HEPA filter is made out of micro filter material which removes very small particles below 0.3 microscopic particles such as the radioactive dust in atomic plants. The Washable HEPA filter is a mainstay in areas that require clean air such as hospitals clean rooms and high-tech manufacturing plants. This filter is an OEM part which is made by the same manufacturer as our Ionic HEPA air purifier units. The best part of these replacement parts is that you can wash it and as long as you wash delicately can be used for years on end. This filter is an OEM part which is made by the same manufacturer as our Ionic HEPA air purifier units. Specifications . 6.5 in. inside width. 7.875 in. outside width . 7 in. height top to bottom inside fit . 8.5 in. height top to bottom outside fit