The story behind those soft-shell puffy Guardian Caps players have been wearing
NFL players experimenting with 'Guardian Caps' to prevent head injuries
NFL report: concussions dropped 50 PERCENT when players wore new 'Guardian Caps' over the summer
NFL: Concussions dropped by more than 50% among players who wore Guardian Caps during summer
[Smith] NFL says positions wearing Guardian Caps saw 52% decrease in concussions : r/nfl
NFL hopes to reduce head injuries with helmet experiment
Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN
Coverage of the NFL in Guardian Caps
What are Guardian Caps? Shadow Hills football using new device to reduce head injuries
Coverage of the NFL in Guardian Caps
The story behind those soft-shell puffy Guardian Caps players have been wearing
Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN