So far so good, made the garage door quieter I did not change the lowest roller as I did not want to mess with the cable or bent the rails, will see how long they last, installation was straight forward forward, plenty of videos on how to do it, just be careful with the lowest rollers if you change them.

The rollers have closed bearings to keep dust out and grease in. Replaced all 12 plain steel rollers on my 8' garage door after upgrading the old chain-drive opener with a belt-drive. These rollers were just the icing on the cake. They're definitely quieter than the all-metal rollers, but you won't even notice if you have a chain-drive opener.

The rollers are quiet and roll smoothly. I used a 12 pack to replace the rollers on a 30 year old steel 15' garage door. The old rollers were also nylon and weren't too noisy but most of them were worn out to the point that the bearings failed. These new rollers were easy to install. I removed three bolts from one roller bracket, removed the bracket and old roller, slid the new roller into the bracket and then reinstalled the bracket with the three bolts.
Don't try to remove more than one bracket at a time and be very careful replacing the bottom roller that is on the bracket that the cable is attached to. This bracket will be under a great deal of tension from the spring so be sure to raise the garage door fully to relieve the tension before trying to replace that one. Hire a professional if you are unsure of how to safely replace the rollers.
The rollers appear to be of good quality. I compared them to my old Clopay rollers and they appeared identical but the real test will be how long the bearings last.

I bought 24 for two 8' doors. Photos showed '6200ZZ' stamped on the bearings in the advertising but there are no stampings on the actual bearings in the wheels being sold. There are visible tooling marks and some dings on the faces of the bearings and shaft end and the wheel coverings feel kind of soft for a durable nylon. 'Nylon shell' now has me believing it's a coating over a steel wheel. They roll nicely and certainly are quiet. I have no real valid complaints about them after the first week, only some questions in the back of my mind. Time will tell if they are what they say they are. I almost gave a 3 because I'm now thinking they are foreign knock offs of lesser quality after reading over some descriptions again, but that wouldn't be fair. I might be willing to give a 5 if I could see 10 years into the future and they truly are as durable as advertised.

These rollers greatly reduced the noise on my overhead garage door