With the 49ers uncertain how much time rookie Reuben Foster will miss, the team reportedly brought in linebackers Sean Spence and Donald Butler for a workout on Tuesday.
News of the workouts was first reported by ESPN.
Spence, drafted by the Steelers in the third round of the 2012 NFL Draft, spent last season with the Titans. In 15 games, he recorded 35 tackles and three sacks.
Butler is a six-year vet with 85 games and 67 starts under his belt. After five seasons with the Chargers, he played for the Dolphins in 2016.
The 49ers are looking for insurance while Foster recovers from a high ankle sprain.