I had looked everywhere for something that I could use with my rather heavy but very comfortable upholstered dinning room chairs. These are small enough and look and operate great. The feature these have that the others I found on line and in stores did not, was that I could use a drill with a smaller diameter so there was less chance that I was compromising the strength of the chair legs.
These are almost exactly like the originals. Very well made and with quality bearings for smooth rotation. While a bit on the pricy side they are hard to find to replace broken ones to keep the original look of the item using them.