The 49ers signed LB Clark Haggans to a one-year contract and placed LB Parys Haralson on the injured reserved list, they announced Monday.

Haralson was kept out of the team’s final preseason game against San Diego on Thursday due to an unknown injury. He was taken out of the team’s third preseason game after suffering what appeared to be a left arm injury. The seventh-year pro started every game last season at OLB, but was expected to backup Aldon Smith this season.

Haggans spent the past four seasons with Arizona after an eight-year stint with Pittsburgh. The Cardinals released him on Friday when the rosters needed to be trimmed to 53 players.

The team had a few other options at OLB, namely Eric Bakhtiari, who led the team with 2.5 sacks during the preseason. They also have seventh-round pick Cam Johnson on the practice squad.

Neither player has the experience of Haggans, who has started 104 games in his career.

Follow 49ers reporter Kyle Bonagura on Twitter: @CBSSportsNFLSF and @KyleBonagura

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