This water filter removes chemicals and contaminants from your drinking water resulting in clean tasting and clean smelling water. We recommend a new filter every six months for optimal water drinkability and flow. Use with Fisher & Paykel Refrigerator Models beginning with: E442 RF610 RF522 E402 RF201 RF402 RF135 RF170 RS36 RF540 RS9120 RF605 RS90 RS36 RS6121 RS7621 RS4621 RS3084 RS2484 RS1884. If you have an older refrigerator model you may need to use part no. Please check your filter for the part number before purchasing.