Rolls do not align when changing direction. This causes the workbench to tip over when I extend the table and change direction to push it back. With a 500lb lathe on a workbench, this becomes very dangerous. I would not recommend using these rollers on a bench or object unless you are strong enough to balance them when changing direction. I am very disappointed in these reels as they have been described as capable of carrying a total load of 840lbs. I bought two sets and was using one when I discovered this instability. I am returning the unused set and removing the used set from my bench which I would return even if I had not already used it. I will look for the best solution.