The DV PRE CP is the replacement filter for the Aquasana drinking water filter system's diverter pre-filter. If your drinking filters clog easily or your water is especially cloudy and full of sediment, you should consider the diverter pre-filter to help extend the life of your filter cartridges and improve the filtration efficiency. The diverter pre-filter works on the AQ-4000 series, AQ-4600, AQ-4500, AQ-4501 series, and AQ-4601 series of drinking filters.Replacement filter for the Aquasana Diverter Pre-Filter to prevent dirt and sediment from entering the main filter.