I used them to replace cracked plastic wheels on my old cheap mechanic's seat. These wheels had half as many bearings as the original wheels and were generally cheaper. The metal on the bearing ring is so thin that when it is tightened it deforms the metal and the bearings are seized. To prevent this I had to use shims so they pressed against the bottom of the shaft and not the bearing ring. It also didn't roll as easily as it used to because of the cheap wheels.