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EXPLAINER: NFL using helmet caps for player safety, research
NFL Presents: League-wide Guardian Cap Use to Reduce Head Impacts
Guardian Caps: NFL requires use of helmet cover at training camps to reduce head injuries
Guardian Caps Guardian Sports
Guardian Sports - Guardian Caps Testimonials
NFL reveals data of rise in concussions for 2022 season
Asked and Answered: Aug. 8
Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN
Arizona Cardinals' J.J. Watt critical of Guardian Cap: 'Feel like a bobblehead' - ESPN