Variable pitch offers both low-speed torque and all-out high speed in one impeller Exclusive hub-end water seal keeps the nasty stuff out of precious parts Enhances all-range maneuverability with no slippage in water hookup Constructed of ultra high-strength, corrosion-resistant stainless steel Mirror-smooth finish and polished hub resists cavitation Original seal required. Choose impeller based on level of engine modification: Limited or Modified. See appropriate columns in chart. Lower pitch impellers recommended for high altitude, pulling or freestyle applications. Impeller pitch is determined by casting, not bending.