NFL hopes to reduce head injuries with helmet experiment, FOX 4 Kansas City WDAF-TV
Certain NFL players must wear Guardian Caps through second preseason game
What Pros Wear: Guardian Caps What are Those Helmet Covers Being Worn in Practice? - What Pros Wear
Rising concussion awareness leads one high school to invest in high-tech football helmets, Sports
Guardian Caps: NFL requires use of helmet cover at training camps to reduce head injuries
NFL expands rule against misuse of helmet; Guardian Caps required in regular season, postseason
Funky-Looking Guardian Caps Rejected by NFL for Regulation Play, OK'd for Practice - Core77
Funky-Looking Guardian Caps Rejected by NFL for Regulation Play, OK'd for Practice - Core77
What Pros Wear: Guardian Caps What are Those Helmet Covers Being Worn in Practice? - What Pros Wear
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