EXPLAINER: NFL using helmet caps for player safety, research
Puffy, spongy Guardian Caps could help curb NFL head injuries - The Washington Post
NFL's top doctor does not expect Guardian Caps to be worn in games - NBC Sports
Chicago Bears: Why players are wearing padded helmets
NFL executive hints that Guardian Caps could eventually be worn in games, along with position-specific helmets
Guardian Caps: Why some NFL players are wearing them in training camps
KTTC In-Depth: Guardian Caps in high school football
Robert Saleh dislikes the new Guardian Caps: And he has a point
Bombers set to don Guardian Caps” on helmets at training camp