Carbon Activated Pre-Filter 4-Pack for use with The GermGuardian FLT4825 HEPA Filter, AC4800 Series, Filter B by Complete Filtration Services Carbon Activated Pre-Filter 4-pack Made in the USA From CFS (Complete Filtration Services Inc.) These Filters Are For Use With The GermGuardian FLT4825 HEPA Filter Each filter is 4.8"x15.75" Heat Sealed Bag Insures Freshness