Guardian cap' to prevent head injuries mandated for practices, CFL says
Why the Ticats are wearing those giant helmets at practice
NFL reports reduction in concussions among players who wore Guardian Caps in preseason - The Athletic
NFL exec suggests Guardian Caps worn to protect players during practices could one day debut in games
Guardian cap' to prevent head injuries mandated for practices, CFL says
Padded helmet cover shows little protection for football players - Scope
Guardian Caps', NFL's Most Recent Attempt At Preventing Head Injuries
NFL hopes to reduce head injuries with helmet experiment