Culligan ac-30, AC30, ac-15, AC15, reverse osmosis (ro) replacement water filters includes sediment, carbon block and 3/8 inch quick change post inline filter. Carbon block made from high purity coconut shell. Sediment filter made with 100% high purity polypropylene. Inline post finishing coconut shell GAC water filter is nsf 2 inch x 6 inch with 3/8 inch quick connect qc ports. To maximize filter system performance, be sure to replace approximately every six months, depending on local water quality. *Please note the replacement membrane is not included.