With barn door hardware becoming popular, there are more and more people selling it from the at home builder to professional businesses.
So what is the difference? To answer that question, there is a lot of differences. Many are building hardware from inferior makeshift wheels that you should be aware of before purchasing. In many cases you will find barn door hardware built from V groove pulley wheels that are designed for running a v belt, while others use v groove wheels designed to roll on a floor rail.
Here are some examples: 
The first example is a zinc aluminum alloy wheel that is commonly used on compressors. Although it looks kind of cool, there are some things to consider. First off, look at the center hole. It has no bearings or sleeve. The problem is that Zinc Aluminum is soft and a steel bolt or shaft will eventually wear out the softer wheel hole. It can squeak and requires more oil maintenance. This style wheel is also known to crack and warp. You can also notice by the lock screw that the wheel is designed to be fixed to a shaft and not turn on it.
Next up are wheels designed to roll on the floor on top of angle iron. 
This type of wheel is typically made of cast iron, comes in various sizes and may or may not have spokes. They can look neat but are clunky, heavy and noisy. Some of the more popular companies will even use these as a retrofit to barn doors.
In addition, they typically have needle bearings that roll around a steel shaft or bolt. Although better than the previously mentioned Zinc Aluminum casted wheel with no bearings, the needle bearings leak and require annual greasing. Notice the grease fitting on the lower 5 O Clock position. The last thing you want is grease dripping onto your barn door or floor.
I.A Décor, takes pride in developing barn door 
hardware sets with wheels specifically designed for barn doors. Our wheels are lighter, can be purchased in high quality composite ‘Hush Puppy’ wheels or even solid steel billet, not cast shown here.
Our wheels also are much smoother, quieter and require no maintenance as they have dual sealed ball bearings and a shaft designed specifically for the bearings.
Visit us at http://www.iadecor.com for more information on our high quality barn door hardware.
I.A Decor 