This kit provides the filters needed for proper annual maintenance of your Amairicare Portable Air Cleaner, Four 3/16"" thick non woven polyester Activated Carbon impregnated pre-filters, Two 1/2"" thick non woven polyester Activated Carbon inner blankets, Pre-filters should be changed every 3-6 months and inner blanket filters every 6 months, SKU: AMAR030