This year's Six Nations will adopt the 20-minute red cards trialled during the autumn.
For the first time in the tournament, players sent off for technical violations can be replaced by a teammate after 20 minutes in an initiative to punish players, not teams.
However, referees can still award full and permanent red cards for intentional and serious foul actions.
Following its successful debut during the Autumn Series of Nations, referees will continue to explain any important decisions within games to viewers through the microphone.
To speed up the game, kickers have 60 seconds after a try is scored to make conversions, while scrums and outs must be formed within 30 seconds.
A global legal trial designed to protect the two halves of the party at the Rocks, Strikes and Knives rule will also come into force for the Six Nations.
The Six Nations begins with Wales' trip to France on Friday 31 January. Scotland hosts Italy, and England travels to Ireland the next day.
