England lock George Kruis has signed a new three-year contract with Aviva Premiership champions Saracens.
Sarries announced that Kruis' new deal will extend his stay at Allianz Park until 2021, while South Africa international prop Vincent Koch has signed an extension for the next four years until 2022.
The new deals follow terms recently agreed by club captain Brad Barritt and Saracens' senior coaching team, led by rugby director Mark McCall.
Kruis and Koch played key roles in Saracens' title success this season and last year's Champions Cup final triumph, while Kruis was also part of the 2016 domestic and European double-winning team.
Koch, who has won nine caps for South Africa, joined Saracens in 2016. Kruis is a Saracens academy product.
"It was an easy decision to make, really," Kruis said. "I've progressed so much in my time at Saracens and we've achieved so much as a group over the last few seasons together.
"It is a hugely-exciting time to be involved here, we've got a massively-talented group of guys who are all hungry to keep improving. I am really proud to be part of that."
McCall added: "We're delighted that Vinnie and George have signed new deals with the club.
"Both of them are phenomenal assets to the club, and we look forward to seeing them continue to develop in a Saracens shirt over the coming seasons."
Kruis, who played in one Test for the British and Irish Lions on last summer's New Zealand tour, featured in four of England's NatWest 6 Nations games this season.