This is the 11x6 3-Blade Propeller from Master Airscrew. COMMENTS: When using 3-blade propellers, avoid high RPM aerobatic manuevers such as snap-rolls. The general rule when replacing a 2 blade prop with a 3 blade is subtract 1 from diameter and increase pitch by 1 if possible. Adjust to 2 for larger diameters 14 and up. jxs 08/23/11 ir/jxs