Restricted free agents are obligated to re-sign with their team if the team is willing to match their highest offer.
Ex. If Lebron was a restricted free agent and the knicks offered him 100 million 6 year deal. Cleavland could match that offer and retain Lebron and the Knicks could then up the offer but CLevland could match again and stop Lebron from leaving. Good thing he will be unrestricted!
nice good news to hear