It was not a simple replacement.   The door knob mechanisms  are not round so all of my doors had to be carved out so the mechanism would fit into the existing hole.  Not sure if you can see in the picture, but the flat part of the mechanism is wider than the round part.  And the size of the difference is inconsistent between sets.  More work than I anticipated, but knobs are pretty, smooth operation and I finally have matching hardware throughout the house.