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Only if your wheel is not hucentric. Also, it is not necessary, but highly recommended. It prevents wheel movement which in turn causes sterring wheel vibration...
You will most likely need a 60.1mm to 73mm ring. The 60.1 is the SC hub size and most "generic" hub sizes on wheels are 73mm. You usually need only the 2 front, but I usually suggest going with all 4...