Less noise, more thrust! Complete kit to upgrade your side-power 55S thruster from a 4-blade prop to the newer, quieter & more efficient 5-blade Q-prop. Can be adapted to all 55S models produced after 1998. Noise reductions of up to 75% measured in controlled environments The expected & tested normal noise reduction in average installations 20 to 40% Will be delivered on all sidepower models during 2008 except the SP550 Upgrade kits are available for most SP Series thrusters with special adaptors Actual noise reduction will vary with boat type & thruster installation Material: Composite Propulsion System: 5-Blade Includes: (1) Q-Prop, (1) Adapter, (1) Zinc Anode with Bolt, (1) Propeller Drive Pin, (1) Propeller Lock Nut, (1) Propeller Washer