The story behind those soft-shell puffy Guardian Caps players have been wearing
NFL players don Guardian Caps, designed to protect from concussion
Staples football pioneers use of 'Guardian Caps'
Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN
Guardian Caps are the latest effort to address CTE, football concussion concerns
NFL hopes to reduce head injuries with helmet experiment
Guardian Caps Guardian Sports
What are Guardian Caps and how are they helping football teams?
NFL executive hints that Guardian Caps could eventually be worn in games, along with position-specific helmets
What Pros Wear: Guardian Caps What are Those Helmet Covers Being Worn in Practice? - What Pros Wear
Colleges add Guardian football protective helmet cap - Sports Illustrated
Guardian Cap Results: “Exceeded Our Expectations”
Coaches approve of the Guardian Cap // Guardian Sports
college football Archives - Guardian Sports