NFL executive hints that Guardian Caps could eventually be worn in games, along with position-specific helmets
Arizona Cardinals' J.J. Watt critical of Guardian Cap: 'Feel like a bobblehead' - ESPN
Guardian Caps Guardian Sports
NFL CMO Dr. Allen Sills calls kickoff rule 'stopgap' measure, talks future of playing surfaces, Guardian Caps
Guardian Caps: Why some NFL players are wearing them in training camps
EXPLAINER: NFL using helmet caps for player safety, research
After being cut multiple times, Cardinals WR Greg Dortch makes headway towards roster spot
Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN
So what exactly is that black padding on the Syracuse football helmets seen during practice?