PetsN'all Waterfall Replacement Filters Columnar granular activated carbon removes odors and particles and provides fresh, pure water Each filter keeps the water clean and fresh for 30 days Double the cleaning power  casing catches hair, food particles and other larger debris, while the carbon filter removes odors, chemicals and bad taste Designed for use with the PetsNall Waterfall Filtration Circulating Pet Drinker sold on Amazon Simple to install  just slide the filter in place