The story behind those soft-shell puffy Guardian Caps players have been wearing
NFL players beginning to adopt protective Guardian Caps over helmets at practice - NBC Sports
Robert Saleh dislikes the new Guardian Caps: And he has a point
NFL training camps: Guardian Cap players are wearing over helmets, why
Eagles players on Guardian Caps: 'We look a little goofy,' but all for safety
Guardian Cap debuts during minicamps in effort to reduce avoidable head contact
NFL hopes to reduce head injuries with helmet experiment - Seattle Sports
NFL: Concussions dropped by more than 50% among players who wore Guardian Caps during summer
NFL Introduces Guardian Caps At First Week Of Training Camp - The Sports Credential