The Brita Pitcher Replacement filter cartridge fits the Brita Pitcher Classic, Riviera, Slim models and other Brita products that call for the OB03 filter cartridge. Tested and Certified by the NSF the OB03 model meets the following standards; NSF/ ANSI Standard No. 53 reduction of Lead, Mercury. Standard No. 42 reduction of Chlorine Taste and Odor Zinc. Cartridge need to be replaced every 40 gallons or 2 months if used with water cooler 2 filters are required and they should be changed every 80 gallons or 4 months.