Carbon Activated Pre-Filter for use with the GermGuardian FLT4825 HEPA Filter, for AC4825 Air Purifiers, Filter B, Pack of 4, By Breezeco Carbon Activated Pre-Filter will extend the life of your Air purifier by Preventing dust from flying into your filter The Breezeco Pre Filters is thicker than the ones that comes with the machine, it will remove common household odors Easy to attach and sticks well Each Carbon Filter measures 4.8"x15.75" and is designed to be a direct replacement for existing Pre-Filter Made in USA