The Giants agreed to terms with David Baas, according a league source.
The 6-foot-4, 330-pound Baas started at center and left and right guard in six seasons for the San Francisco 49ers. The 29-year-old was the starting center last season, his first at that position.
He started 24 games at left guard in 2008 and 2009; before that, he made 13 starts at right guard.
The move was first reported by the Sacramento Bee.
The Giants have been trying to get under the salary cap so they can re-sign some of their own free agents, such as running back Ahmad Bradshaw, defensive end Mathias Kiwanuka, wide receiver Steve Smith and tight end Kevin Boss.
Ohm Youngmisuk covers the Giants for ESPNNewYork.com.