Oakland Raiders wide receiver Antonio Brown has reportedly filed a grievance against the NFL for banning a helmet he wore throughout his time with the Pittsburgh Steelers since it's no longer certified by the National Operating Committee on Standards for Athletic Equipment (NOCSAE).
ESPN's Adam Schefter reported Friday league sources believe Brown, who will argue his case in front of an arbitrator, may be sitting out portions of training camp because of the helmet issue in addition to the extreme frostbite he reportedly suffered while using a cryotherapy chamber in France last month.