They're cheap and work, but some of them have VERY play. Others seem to have their breeds off-axis, so they wiggle. However, this is difficult to test due to the way I use them. I make wind speed and direction sensors out of it. The direction is not very sensitive to wobble because the rate of change is small, but the wind speed is very sensitive because the wobble causes abrupt changes in resistance, and the wobble significantly reduces performance. If I were to use them in high speed applications where they would be put under a bit of a load I would expect them to perform decently. Also, they do not start at very low wind speeds due to initial friction. What I really need is bearings for precision instruments, but I just can't find a reliable supplier.