PUREBURG 2-Pack Replacement High-efficiency 4-Stage Filtration True HEPA Filters Compatible with Envion Therapure TPP440F , TPP440 TPP540 TPP640 TPP640S Air Purifiers Compatible With Therapure TPP440 TPP540 TPP640 TPP640S Compatible Part : Therapure TPP440F After Replacing the filter , please hold down Timer + Power On button for 3 seconds. The clean filter light will go off Disclaimer: This product is a generic item that is designed to replace the original part. Any brand names or logos are the registered trademarks of their respective owners. Any use of any brand name or model designation for this product is made solely for purposes of demonstrating compatibility.. PUREBURG - Pure Your Breath! We value your satisfaction. If you have any problems using our product, please always contact us.