Turning Point - Express Mach4 Stainless Steel Propeller - Left Hand - 4-Blade - 15.3" x 13 Pitch - EX-1513-4L - 31501340. The Prop that put the "four" in Performance! Turning Point's Four Blade revolutionized the aluminum propeller market when introduced over 6 years ago. No one had ever produced an aluminum propeller with two different blade shapes (they call it Dual Geometry) for 90-300+hp applications. This prop is uniquely engineered with two blade geometries: two blades utilize the high per