Waterway 4.0 HP Executive Spa Pump Wet End [2" MBT X 2" MBT] [48 Frame] (310 1910) airsupply The multi model compatibility gives this The multi model compatibility gives this lock ring its practical value because structural closure parts work best when they match the original filter body relationship closely Helps engage application specific socket or retaining points more securely A wet end like this is useful because it restores the full hydraulic section of the pump in one matched assembly Frame specific replacements are especially important in Executive pumps because similar horsepower models may still require different wet end layouts