I used these in combination with the frog balancer for balancing 3rd party phantom 3 props, which needed lots of balancing. It would be unlikely that it would be useful for other balancers. Only one end of the shaft touches the magnet, while the other end just is suspended by the magic power of magnets. It does tend to droop down from the horizontal a bit, but this doesn't seem to affect the balancing. By squeezing the arms of the frog balance together you can make the shaft more horizontal as the magnet at the prop end is closer and attracts the shaft and prop more strongly.
It seemed to work quite effectively and hard to go wrong at that price.extend the usability of your frog balancer by adding these. good job hkThey fit into the props nicely, but the magnet pulls on the metal prop insert making it impossible to balance correctly. No matter how you spin the prop it always returns to same spot because of the magnet. I was hoping this would replace my tru spin balancer and phantom balancing shaft. Don't waste your money on these.