NFL: Concussions dropped by more than 50% among players who wore Guardian Caps during summer
Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN
Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN
Eagles players on Guardian Caps: 'We look a little goofy,' but all for safety
NFL announces more steps to reduce head injuries
Can Custom-Fit Football Helmets Protect Athletes From Brain Trauma?, Chicago News
Cam Rising Will Be Wearing New Technology Helmet In 2022
Ban on helmet covers sparks controversy
Arizona Cardinals defensive end J.J. Watt not fan of the new league-mandated Guardian Caps on helmets
Funky-Looking Guardian Caps Rejected by NFL for Regulation Play, OK'd for Practice - Core77
High school football looks to Guardian Cap for head safety
Tennessee football: UT Vols use Guardian helmet covers
GameBreaker-Pro Soft Shell Helmet Buy Pro Soft Shell Headgear - GameBreaker