a651, if you please, go to an older Forum named Raining Airplanes!!!!! , find post #5 by a nice guy named JimRoss, and you will see what a sharp plastic prop can do to you ( or somebody else ), and I have seen worst. Be extra carefull with those Nylon or Fiber props, I rather loose two bucks, than loosing one finger. If you dull the edges with sandpaper that will help a bit, just remember to balance them. Good luck !