oGeee Carbon Pre-Filter for use with The GermGuardian FLT4825 HEPA Filter, AC4800 Series, Filter B (1) These PreFilters are designed to fit FLT4825 True HEPA Replacement Filter for AC4800 Series, Filter B desinged to be a direct replacement for existing Pre-Filter Keep trapping large particles in air and filter off such as dust, fibers, lints, puff, smoke. The Replacement filter is very easy to install. Each filter is 4.8"x15.75"