The casters themselves are a big improvement over the standard ones on low-to midrange office chairs. Operation is smooth and stable. What may need doing is to modify the chair's sockets. In my situation they had to be made larger, which was a careful operation, using very graduated drill bits, but it worked perfectly. Anyone basically handy need not fear the process; just take the proper time to do it and enjoy the results.
Rating: [5 of 5 Stars!]