England internationals Mako and Billy Vunipola have extended their contracts with Premiership champions Saracens until the end of the 2021-22 season.
The pair helped Sarries to three league titles in four years and European Champions Cups in 2016 and 2017.
Mako, 27, has won 51 caps for England, while Billy, 25, has played 36 times.
“Both players have made outstanding contributions to Saracens over a number of years,” director of rugby Mark McCall told the club website.
“They’ve played a very significant role in the development of the group both on and off the field and naturally we’re thrilled they’ve committed their future to the club for another four years.”
Prop Mako has made 144 appearances for the Allianz Park side since joining from Bristol in 2011 and said it was “pleasing to get the opportunity to play here at a great club”.
Back-row Billy, who joined Sarries from Wasps in 2013, has played 85 times and called the decision to extend his contract “straightforward”.