CFL introduces mandatory extra helmet protection for multiple positions. As well as other new health & safety measures. : r/sports
NFL training camps: Guardian Cap players are wearing over helmets, why
Puffy, spongy Guardian Caps could help curb NFL head injuries - The Washington Post
Guardian cap' to prevent head injuries mandated for practices, CFL says
NFL hopes to reduce head injuries with helmet experiment
EXPLAINER: NFL using helmet caps for player safety, research - The San Diego Union-Tribune
NFL hopes to reduce head injuries with helmet experiment
What are Guardian Caps? NFL's latest padded helmets for added safety
NFL's use of Guardian padded helmet caps in camp draws support and skepticism - The Athletic
The Do's and Don'ts of NFL OTAs, News, Scores, Highlights, Stats, and Rumors
NFL's use of Guardian padded helmet caps in camp draws support and skepticism - The Athletic
Guardian Caps are the latest effort to address CTE, football concussion concerns