Big Brand carbon cartridges are a one-step carbon and filtration treatment. These cartridges eliminate the problems associated with loose carbon treatment and the need for a separate filtration system. The standard cartridges measure 23/4" OD with lengths varying from 4" to 40" with flow rates up to 2 1/2 gpm. These cartridges are designed to be used in either single or multi-tubed vessels. Big Brand carbon cartridges are available is 4 different styles: Style GC is an outer wound cartridge which utilizes a special high grade activated granular carbon with a very low sulfur content. Style CP is also an outer wound cartridge which features layers of paper impregnated with activated powdered carbon. Style C is a porous polyethylene shell containing high grade activated granular carbon and Style M features an outer layer of polyolefin webbing with an impregnated carbon powder interior.