I just bought set of this. Am very impressed by performance just one tip for designer. If you could do a little adjustement in project because clockways prop has reinforcements inside central coon like cross bars across mounting shaft what make it strong and easy for bslancing. The other couterclockways prop has only coon and shaft mount inside coon without cross bars for reinforcement.possible because of this when i was trying to ballanced this prop ,was gone very far out of ballance and exploded inside tube. It was about 12000rpm ,the second one going ease up to 16000rpm.