Impeller. Pump:F95. Material:Neoprene (for cooling). Outer Diameter:3.74". Inner Diameter:Splines. Width:5.12". A worn or damaged impeller can cause system failure or engine breakdown. SPX's Johnson Pump brand impellers are developed and manufactured for maximum flow and long life. With a genuine spare impeller you can also be sure that you are getting the quality required by engine manufacturers and professionals.