Review on Enhance your Sliding Doors with the SMARTSTANDARD Adjustable Roller: The Ultimate Guide by Doug Small

I bought this for a barn door track. Good: This device has many variable adjustments, so it leaves many sizing options. will work. The bad thing: Since it goes under the door, you need at least as much space between the floor and the door, otherwise it hangs. If your floor is not perfectly level, there will be a large gap under the door. I won't use it more than I wanted. Plastic rollers on metal pins. I doubt they will have a long life. (Heavy barn door + something made of plastic = failure)