NFL Network: Guardian Caps in use at training camps
History Of The Helmet: Then And Now - Gridiron Heroics %
Puffy, spongy Guardian Caps could help curb NFL head injuries - The Washington Post
Puffy, spongy Guardian Caps could help curb NFL head injuries - The Washington Post
NFL exec suggests Guardian Caps worn to protect players during practices could one day debut in games
What Pros Wear: Guardian Caps What are Those Helmet Covers Being Worn in Practice? - What Pros Wear
NFL says positions wearing Guardian Caps saw 52% decrease in concussions - NBC Sports
NFL executive hints that Guardian Caps could eventually be worn in games, along with position-specific helmets
Football helmet joins fight vs. head injuries - The Boston Globe
Florio PFT] The Guardian Cap apparently works. But if a player asks to wear it in a game, the league would say no. : r/nfl
Arizona Cardinals defensive end J.J. Watt not fan of the new league-mandated Guardian Caps on helmets