NFL players wear Guardian Caps to reduce head trauma during training camp
NFL introduces Guardian Caps across league to limit number of brain injuries in preseason
NFL's use of Guardian padded helmet caps in camp draws support and skepticism - The Athletic
NFL hopes to reduce head injuries with helmet experiment, Sports
Chicago Bears: Why players are wearing padded helmets
Smith] NFL says positions wearing Guardian Caps saw 52% decrease in concussions : r/nfl
If a player wanted to wear a Guardian Cap during a game, the league would prohibit it
More teams practicing with Guardian Caps, Sports
Bombers set to don Guardian Caps” on helmets at training camp