Former Steeler and current Raider Antonio Brown has reportedly filed another grievance against the NFL regarding his helmet.
The receiver has already lost a previous filing against the league as he sought to wear his Schutt Air Advantage helmet, which he's worn his entire nine-year career.
The seven-time Pro Bowler was allowed to wear the helmet last season under grandfathering of the rule, along with Green Bay Packers quarterback Aaron Rodgers and New England Patriots quarterback Tom Brady.
Brown has argued the new model helmets restricted his peripheral vision.
Monday was his first time back at training camp as he sat out in protest over the helmet issue.