The AP917HD-S Replacement Cartridge for the AP904. Designed for sediment reduction (5 micron nominal), chlorine taste & odor reduction and scale inhibition up to 20 GPM. At 10 GPM average flow rate, this product performs to 75% efficiency over its life (100,000 gallons) based on manufacturers test protocol for chlorine taste and odor. This cartridge also includes a scale inhibition media to help reduce the potential build-up of hardness scale in water heaters, pipes and water using appliances. 20 GPM Flow Rate. This product is not designed for potable water with precipitating iron, bacteria or chloramine present. Alternative Part #: 56210-08, 5621008 Cuno part number: 5621008, 56210-08 Grainger part number: 10U924