What is the NFL's Helmet Policy Driving Antonio Brown's Absence?

Tom Brady joined Antonio Brown with concerns over the new helmet, voicing his displeasure in April.

Antonio Brown is reportedly willing to retire from the NFL if the league doesn't alter its helmet policy. But what exactly is Brown protesting? 

The NFL ran a study of helmet performance in April and identified 11 models that were to be prohibited for the 2019 season. One of those models was worn by 32 players throughout the NFL in 2018, including Aaron Rodgers and Tom Brady. Rodgers and Brady have complied with the new rule, although Brady noted his displeasure in April.

Brown was not one of the 32 players to wear the prohibited model, but he is still not compliant with NFL rules. All NFL helmets must be certified by the National Operating Committee for Standards and Athletic Equipment, and Brown's "helmet cannot be recertified because it is more than 10 years," according to NFL.com's Mike Silver.

Oakland's wideout has reportedly worn a "Schutt Air Advantage helmet" throughout his career, according to ESPN's Adam Schefter. The helmet has been discontinued by the company and is uncertified by the NOCSAE. 

Even if Brown finds a suitable helmet, there is no timetable for his return to the field. The four-time All-Pro has not participated in Raiders' camp due to a foot injury suffered in a cryotherapy chamber.