Seeking to reduce head contact, NFL mandates use of Guardian Cap helmet for early portion of training camp - ESPN
NFL Players Seen Sporting Futuristic New Helmets During Training Camp (PICS)
What Pros Wear: Guardian Caps What are Those Helmet Covers Being Worn in Practice? - What Pros Wear
The story behind those soft-shell puffy Guardian Caps players have been wearing
Guardian Cap Debuts at NFL Training Camps League-wide
NFL players experiment with 'Guardian Caps' to protect heads – The Oakland Press
NFL, Oakley come up with face shields to protect players
What are the padded helmets players are wearing at NFL training camps?
Patriots, rest of NFL wearing cushioned helmet caps at training camp, per new mandate - CBS Boston
Guardian Caps: Why some NFL players are wearing them in training camps
Guardian Cap Use a Concern for Watt, Saleh Early in Training Camp - Sports Illustrated
Guardian Cap used by football teams to protect against head injury – The Denver Post
How a soft-shell helmet is limiting the risk of concussions at Rutgers football camp
NFL hopes to reduce head injuries with 'goofy' helmet experiment
NFL CMO Dr. Allen Sills explains importance of mandated guardian caps during training camp