ImpellerPump:F2Material:Nitrile (oil resistant)Outer Diameter:1.29″Inner Diameter:0.31″/FlatWidth:0.50″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. Quick Guide (pdf)Owner’s Manual (pdf)