I purchased a few of these for a little 30" wingspan pylon racer type plane. In flight they work fine, they did need a lot of work to get balanced, but they did eventually balance out. The downside is that they are very fragile; i.e., they are made of a type of plastic that cannot be bent without snapping, very brittle and weak. I broke a prop on every other landing into tall 2-3ft high grass. The plane never touched the ground, but the pressure of the grass pushing on the prop blades caused stress marks (the plastic turned white) right near the hub. On the next flight and subsequent landing the prop was broken. If you are grass/belly landing I wouldn't recommend these props, otherwise they should work ok. (Posted on 1/24/2014)