Val Pak 1 1 2" MPT Spring Return Line Check Valve (V20 339) pentairpool The 25 square foot rating The 25 square foot rating and 1 1 2 inch slip connection give this filter practical value because correct sizing and connection fit matter in preserving the intended flow and installation relationship of the system the flow path assembly is often the part that brings it back This replacement is especially useful when the original valve has started sticking restoring the check valve can help improve overall system behavior and reduce the kind of flow reversal that creates nuisance issues during operation or shutdown