PUR’s filters are made with activated carbon to reduce chlorine and sediment, and include an ion-exchange resin that helps eliminate lead and copper. For best results, filters should be changed every 40 gallons. While PUR filters rid water of many chemicals, coloration, and bad flavors, they do not soften water or remove fluoride. This package of filters measures 7.9 by 7.6 by 2.7 inches, and weighs 2 pounds. --Jessica Reuling