Abatement Technologies HC1818 H14 Pharmaceutical Grade Gel Seal HEPA Filter MERV 10 the HP300 also requires a Anti Allergy Filters:Two (2) Anti Allergy the HP300 also requires a HEPA Core Filter that removes 99 Abatement Technologies H502 is the 16 x 16 x 2 original equipment manufacturer replacement 2nd stage filter 3 microns) Media Microglass Seal Pharmaceutical grade gel seal on inside channel of header Frame Extruded anodized aluminum Flammability UL 900 Class 1 Filter Stage Final stage Max Service Life 1 500 hours or 2 years — whichever comes first Quantity 1 filter per order Use only Abatement Technologies OEM replacement filters