The Replacement HEPA Filter is a combination filter designed to work with Pure Enrichment’s PureZone Machine. Each of the three layers of this filter provides a unique level of cleaning, HEPA Filter Size is 9.05*8.66*0.78 inch ，Please check your filter size before purchase Long-Lasting-- Use up to 6 months for optimal performance ,Filter Reset Indicator, Lets you know when it’s time to change the filter Replace it every 6—8 monthes If you need any helps, Please feel free to contact us via your order , we will more than happy to help you , Thank you !