SANTA CLARA -- The 49ers signed a new free safety Saturday, and he probably isn't the household name you were expecting: Craig Dahl, formerly of the St. Louis Rams.

Dahl signed a three-year deal upon visiting the 49ers, who also have shown interest in more heralded veterans Charles Woodson, Ed Reed and Louis Delmas. Financial terms weren't immediately known.

"They mentioned they brought in a few other guys but were very select in finding a person in fitting their mold here in San Francisco," Dahl said.

Dashon Goldson fit the role of a hard-hitting free safety the past four seasons as the 49ers' starter, but he signed a five-year deal last week with the Tampa Bay Buccaneers.

"They told me there was an opportunity to play in the voided safety position," Dahl added. "I'm hoping to come in, mesh well with the secondary and fill that void."

With Dahl having made 40 starts for the Rams over the past four seasons, his familiarity with the division appealed to the 49ers.

"He is an experienced veteran with excellent intangibles, who has working knowledge of the NFC West," 49ers general manager Trent Baalke said in a statement.

Dahl (6-foot-1, 212 pounds) recorded four interceptions in 61 games with the Rams.

Said Dahl: "I was privileged to play in the NFC West ... The mentality of the division has changed. It's a lot more physical, more aggressive."

The 49ers are coming off a Super Bowl defeat that further exposed deficiencies with their pass defense. They allowed eight touchdown passes in three playoff games, after yielding only 19 touchdown passes in their 16 regular-season games.

Another potential addition is 10-year veteran cornerback Nnamdi Asomugha, who visited with the 49ers on Friday. Dahl said he won't flinch if the 49ers continue to pursue Woodson, Reed or others. (Delmas re-signed with the Detroit Lions.)

"I'm always open for competition," said Dahl, who entered the league with the New York Giants in 2007 as an undrafted free agent out of North Dakota State.

North Dakota State is where Baalke started his coaching career in 1989 as an assistant, providing an obvious talking point with Dahl during his visit. Most of their chat, however, revolved around how Dahl fit into the 49ers' plans.

Dahl also will be asked to play on special teams, and the Rams used him in the same personal-protector role on the punt unit as the 49ers did with Goldson.

His safety skills, however, could be needed most, and for now his competition at the starting role will be with C.J. Spillman, Trenton Robinson and Michael Thomas.

"It helps me out that I was able to play against most of what we have in the NFC West last year," Dahl said. "Russell Wilson poses a big threat in Seattle. Here with (Colin) Kaepernick leading the reins, he'll do good things for us and the offense in the future."

For more on the 49ers, see Cam Inman's Hot Read blog at blogs.mercurynews.com/49ers.