England internationals Billy and Mako Vunipola have both signed new contracts at Saracens, it was announced Friday.
The brothers have been key figures in the success of the north London side during the past decade.
The English Premiership club did not reveal the length of either No 8 Billy or prop forward Mako's new contracts but Mark McCall, Saracens' director of rugby, said: "Everyone involved with Saracens will be thrilled that Mako and Billy have chosen to extend their time at the club.
"In their own unique ways, they have been instrumental in how we have grown and progressed and have been key figures in the success the club has enjoyed."
McCall added: "Mako is a world-class operator, with an incredible skill set and an innate understanding of the game. His competitive spirit and leadership have helped drive standards within the group and he has the desire and determination to take his own game and that of the team to new levels in the years ahead.
"Billy's level of performance for nearly a decade at the club has been staggering and he has demonstrated great resilience and perseverance to overcome a number of serious injury setbacks over that time.
"He is highly influential on and off the field and has a great feel for what the group needs at any given moment.
"We are grateful to Mako and Billy for the loyalty they have shown to the club."
Billy, who has made 135 appearances for Saracens since joining from Wasps in 2013, has won four Premiership titles and three European crowns during his time with the club.
The 29-year-old, at his best a dynamic force in open play, has won 61 caps for England and also scored a try in Saracens' 2019 European Cup final win over Leinster.
Mako has represented Saracens 187 times since joining in 2011.
The 30-year-old has won eight trophies during his time with the club.
He has also been capped 67 times by England and been selected for three British and Irish Lions tours, including this year's series against South Africa.