Seeking to reduce head contact, NFL mandates use of Guardian Cap helmet for early portion of training camp - ESPN
Ravens Embrace the Funny-Looking Guardian Helmets - Sports Illustrated Baltimore Ravens News, Analysis and More
NFL takes first-ever step to ban some helmets after testing - The San Diego Union-Tribune
Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN
Cowboys Players Wearing Strange New Helmets at Training Camp – NBC 5 Dallas-Fort Worth
Guardian Cap used by football teams to protect against head injury – The Denver Post
It's time the NFL made Guardian Caps mandatory
Have you seen the strange helmets Cowboys players are wearing in camp? Here's the story
The story behind those soft-shell puffy Guardian Caps players have been wearing
Giants react to NFL's new 'Guardian Caps' at training camps - Big Blue View
Guardian Caps Guardian Sports
Guardian Cap: What are and why the NFL asks this safety measure in helmets
Puffy, spongy Guardian Caps could help curb NFL head injuries - The Washington Post
Guardian Caps: Why some NFL players are wearing them in training camps