Rowenta XD6086 NanoCaptur Filter Formaldehyde Remover for PU6020 and PU6010 Intense Pure Air XL Purifier Patented Rowenta NanoCaptur technology destroys permanently formaldehyde emitted by : cleaning products, pressed wood materials, building materials Formaldehyde is considered as the most dangerous home pollutant according to the world Health organization The NanoCaptur yellow granules inside the filter turn red if saturated, meaning it is the time to replace the filter Fits PU6020 and PU6010 Intense Pure Air purifiers - room coverage up to 835 sq. ft. Replace on an average once a year - always monitor color of the granules if brown need to replace the filter