... carbon and filtration treatment. These cartridges eliminate the Activated Carbon Block Filter Cartridges are a one-step carbon and filtration treatment ... 2 3/4" OD with lengths varying from 4" to 40" with flow rates up to 2 1/2 gpm per ... ,25,50,100 D. The Length: 5",10",20", 30" & 40" E.The Diameter: ID 28mm OD 69mm OD 114mm F ...