Description This heavy duty True HEPAMax™ Replacement Filter is for the Winix T1 Air Purifier. Constructed with True HEPA material and designed to remove allergens and VOCs. The HEPAMax™ Replacement Filter is independently certified to be 99.97%* efficient down to 0.3 microns in size.*Based on an independent laboratory test conducted on particles as small as 0.3 microns in size.