Oakland Raiders wide receiver Antonio Brown is not enthralled by the fact that he is no longer allowed to wear his old helmet, and he has filed a grievance with the league as a result.

While a decision is expected this week, NFL spokesman Brian McCarthy took to Twitter to inform the public of the rules.

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“The player can’t practice or play in games with equipment that’s not approved,” wrote McCarthy. “If he doesn’t play or practice, he is in breach of his contract and doesn’t get paid. NFL policy is that helmets have to be certified by NOSCAE. They don’t certify equipment that’s older than 10 years.”

It has certainly been a wild offseason for Brown.

Things began with Brown requesting a trade from the Pittsburgh Steelers, and in March, the Steelers granted his request, sending him to the Raiders in exchange for a third-round draft pick and a fifth-rounder.

Brown then arrived at Oakland's training camp on time late last month, showing up via hot air balloon. He was then immediately placed on the non-football injury list, but was on the list for less than 48 hours before practicing with the team. However, Brown only partially practiced and has not been on the field since, as he has been sidelined due to getting frostbite on his feet as a result of spending time in a cryotherapy chamber without wearing the proper foot attire.

While it was originally believed that Brown was holding out of practice strictly because of the foot problem, the issues with his helmet are obviously another big, and perhaps more pressing, reason, as the 31-year-old has threatened to walk away from the game if the NFL does not permit him to wear his old headgear.