NFL hopes to reduce head injuries with helmet experiment
Football helmet - Wikipedia
So what exactly is that black padding on the Syracuse football helmets seen during practice?
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Guardian Caps Guardian Sports
Smith] NFL says positions wearing Guardian Caps saw 52% decrease in concussions : r/nfl
Puffy, spongy Guardian Caps could help curb NFL head injuries - The Washington Post
Arizona Cardinals' J.J. Watt critical of Guardian Cap: 'Feel like a bobblehead' - ESPN
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NFL executive hints that Guardian Caps could eventually be worn in games, along with position-specific helmets
NFL expands rule against misuse of helmet; Guardian Caps required in regular season, postseason
Guardian Cap debuts during minicamps in effort to reduce avoidable head contact
Why Alabama football players are wearing padded helmets in practice
What are Guardian Caps? NFL's latest padded helmets for added safety
Guardian Cap Use a Concern for Watt, Saleh Early in Training Camp - Sports Illustrated