FREMANTLE has locked away a pair of talented youngsters, with promising tall Brennan Cox and utility Ed Langdon re-signing for two more years. 

South Australian big man Cox has recommitted until the end of 2020 after arriving at the Dockers via a bargain pick 41 in last year's NAB AFL Draft.

As reported by AFL.com.au on Sunday, Langdon has agreed to stay at Fremantle until least the end of 2019, with the Victorian buoyed by the rebuilding club's progress.

Cox has been one of seven debutants this season and the versatile 193cm tall has impressed as a marking target in attack, pinch-hitting in the ruck and, at times, holding down a key post in defence in his eight games.

The 19-year-old earned All Australian honours as a backman at under-18s level.

"He's shown some strong attributes in the football he's played," list manager Brad Lloyd said. 

"He is a good size and a great athlete and he's shown a high level of composure when he's played at senior level, so we're really excited about the role he can play on our list for years to come." 

Langdon was a consistent part of the Dockers line-up in the first half of the season before being hampered by a lingering knee issue.

The 21-year-old played 10 of the first 11 games but was recently ruled out for the season and underwent PCL surgery.

"Ed has an elite running capacity and in the senior games he's played over the last couple of years he's shown the ability to find the ball and impact games in key moments," Lloyd said.

"We're thrilled to see Ed continue at the club and look forward to watching him develop and become an important member of the senior team."

Fellow Victorians Hayden Crozier and Darcy Tucker appear likely to recommit to Fremantle soon, but second-year midfielder Harley Balic is set to request a trade back to his home state after twice taking personal leave this year.