The Brita Pitcher Replacement Filter Cartridge fits the Brita Pitcher "Classic", "Riviera", and "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 for reduction of •-Lead •-Mercury NSF/ANSI Standard No. 42 for reduction of •-Chlorine •-Taste & Odor •-Zinc Cartridge needs 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.