Very weak at the root and snaps easily at half throttle in-flight. Assuming safe rotational speed for these props is - say 65000 divided by prop diameter (9" prop) is 7222 RPM (Max rotational speed with fully charged 3S, using 980KV motor is 980KV x 12.6V = 12,348 RPM). I was only at 40pcnt throttle for hover. I am certain, I did not exceed rotational speed.