Wales coach Warren Gatland will have access to his Grand Slam winners for 13 days before their opener against Scotland at Murrayfield on 8 February after achieving player access he wanted for the RBS 6 Nations.
The major boost to Wales' hopes of retaining the Six Nations title comes after an agreement between the Welsh Rugby Union and the Welsh regions.
Wales also have first call on the players for the entire competition, even though there are two weekends of regional matches during the tournament.
The regions agreed to the terms after meetings at the start of this week.
The 2017 RBS 6 Nations was watched by record numbers of fans
29 March 2017, 12:25pm
After an enthralling RBS 6 Nations Championship of twists, turns, and no small amount of drama on the last day, figures show the RBS 6 Nations is going from strength to strength, year on year, with no sign of slowing down.