fun prop more than anything. They look and sound so cool. very high pitch whine. For performance I wouldn't give then a great rating. I have them on a HK 250 color, kk2.1 mini FC, orange 4ch RX, Afro 30amp ESCs, and turnigy BEAST motors. I would say they have a little more bite than 5040 2 blade bull nose but less than 5050 2 blade bull nose props. blades are very thin and bend easy, I would rate the strength about the same as 5030 gem fan props. I didn't hit anything but I imagine one hit and they will break. I will probably keep a set around just for fun. more novelty than performance.