So what exactly is that black padding on the Syracuse football helmets seen during practice?
NFL hopes to reduce head injuries with helmet experiment
The story behind those soft-shell puffy Guardian Caps players have been wearing
The Lass Word: This Year's Preseason Games Are Actually Important
Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN
Smith] NFL says positions wearing Guardian Caps saw 52% decrease in concussions : r/nfl
NFL's use of Guardian padded helmet caps in camp draws support and skepticism - The Athletic
Football helmet - Wikipedia
NFL hopes to reduce head injuries with 'goofy' helmet experiment
Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN