NFL hopes to reduce head injuries with helmet experiment
NFL Guardian Caps: How Do They Work? – NBC 5 Dallas-Fort Worth
Padded helmet cover shows little protection for football players
NFL hopes to reduce head injuries with helmet experiment - Seattle
Guardian helmets worn in Training Camp
Cowboys Players Wearing Strange New Helmets at Training Camp – NBC
Cowboys seen wearing protective, NFL mandated Guardian Caps at OTAs
NFL's use of Guardian padded helmet caps in camp draws support and
NFL exec suggests Guardian Caps worn to protect players during
EXPLAINER: NFL using helmet caps for player safety, research
Guardian Caps Guardian Sports