ImpellerPump:F8Material:Nitrile (oil resistant)Outer Diameter:3.74"Inner Diameter:SplinesWidth:2.48"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.