Mercury - SpitFire X7 4-Blade Stainless Steel Propeller 12.8" Diameter x 19" Pitch Right-Hand Rotation 4-Blade Stainless Steel Polished Finish 8M0151363. Overview. If you've ever felt that perfect mix of power and precision when your boat hooks up and takes off, you'll understand why the Mercury SpitFire X7 12.8x19 Right-Hand 4-Blade Stainless Steel Propeller (8M0151363) has such a loyal following. It's built for boaters who live for that instant throttle response the kind that sends your boat o