Ben Affleck got a piece of 'practical advice' from Christian Bale about playing Batman

It never hurts to get advice before you go into a big job. And there's probably no bigger role Ben Affleck has signed on for than playing Batman in "Batman v Superman: Dawn of Justice," which hits theaters March 25.

In a recent interview with "Good Morning America," Affleck said that he has gotten advice from two former Dark Knights: George Clooney and Christian Bale.

In typical Clooney fashion, the actor, Affleck says, "gave me some advice which is not repeatable." But Affleck did share what Bale told him.

"I talked to Christian, who just told me to make sure I got a zipper in the suit, which was valuable, practical advice as it turned out."

It probably makes sense to go with the wisdom from the guy who revived Batman to acclaim over three films, rather than the guy whose role in the franchise is best known for a Batsuit with nipples on it.

In the "GMA" interview, Affleck also talked about getting into shape for the role, having to go up against the buff Henry Cavill, playing Superman, as he did in "Man of Steel."

"I saw the first movie he was in and I was like, 'Wow, I don't know if I'm going to be in quite that good of shape,'" Affleck said of Cavill.

Though Affleck said he did end up putting on 20 pounds of muscle for the role.

Watch the full "GMA" interview with Affleck and Cavill below: