Antonio Brown practices with Raiders in a certified helmet, Jon Gruden says

Antonio Brown practiced Tuesday while wearing a certified helmet, Oakland Raiders coach Jon Gruden told reporters.

“He’s all-in and ready to go,� Gruden said of the star receiver who has missed time this summer as he battled the league for permission to use his now-outdated helmet this season. “That’s my understanding. Really happy to have him out here. He’s a great player.�

Multiple media outlets reported Monday that Brown has filed a second grievance against the NFL in an attempt to continue using the helmet he’s used his entire career, one that is no longer meets safety standards set by the league and the NFL Players Assn.

The news broke on the same day that Brown took part in meetings before the team broke camp and a day after general manager Mike Mayock gave him a public ultimatum to be “all in or all out.� A frustrated Mayock told reporters Sunday that Brown was not at camp Sunday because of the helmet issue.

Brown’s agent Drew Rosenhaus disputed that the star receiver had left camp.

Brown is one of several players, including New England Patriots quarterback Tom Brady, whose preferred helmets are no longer certified by the National Operating Committee for Standards and Athletic Equipment. After losing his initial grievance against the league earlier this month, Brown was told he could wear a version of his beloved Schutt AiR Advantage that isn’t quite so outdated.

The seven-time Pro Bowler found one such helmet, but that one was also determined to be unsafe.

Brown’s new grievance claims he did not receive the one-year grace period given to other players with helmet issues, according to multiple media reports.

Rosenhaus told ESPN on Monday that Brown wants to join his teammates but feels the helmet “he’s worn his entire life� is the one that keeps him safest.

“This is his life. He’s risking everything. He’s got a family,� Rosenhaus said. “He’s had a concussion before. This helmet has kept him safe. He’s had brutal hits and we’re just trying to find a way to work it out.�

Rosenhaus added: “The helmet is the most important piece of equipment, and he’s had the same one every single snap he’s played in his football career. It is a major issue for him.�