Aluminium Series Although plastic or aluminium is the lowest-cost option for most engines, these Yamaha propellers provide better performance than other plastic / aluminium propellers because of their precise matching to Yamaha engines. The light-weight and lower cost also makes aluminium propellers an excellent choice as a spare propellers, in case striking an underwater object accidentally damages the primary propeller.   Stainless Steel Pro Series This is the top-of-the-range propeller. It is specifically designed for single engine, high-speed boats that require "bow lift" and significant engine-mounting heights, such as bass boats. The Pro Series propeller blades are designed with high rake angles, progressive pitch and aggressive cupping for excellent mid-range and top-end performance. The exhaust tube includes specially-designed relief holes to improve low-speed acceleration. The Pro Series is available in three pitch sizes for the 70 to 130hp ranges and four pitch sizes for the 150 to 225 V6 models. Besides these there are two specially designed pitches for the 225 Vmax, 250HPDI and Vmax 250 HPDI.   Stainless Steel Black Series These propellers are designed as excellent general-purpose propellers. The steel construction allows for a blade that is thinner, more efficient end more durable than an aluminium propeller. The painted blade both reduce the cost and provide longer zinc anode life in saltwater, by reducing the exposed dissimilar metal surface. They are available in both standard right-hand rotation and left-hand rotation for twin engine applications.