NFL mandates use of Guardian Caps for training camp in 2022 - Cincy Jungle
Arizona Cardinals defensive end J.J. Watt not fan of the new league-mandated Guardian Caps on helmets
NFL's use of Guardian padded helmet caps in camp draws support and skepticism - The Athletic
If a player wanted to wear a Guardian Cap during a game, the league would prohibit it - NBC Sports
Why the Ticats are wearing those giant helmets at practice
Guardian cap' to prevent head injuries mandated for practices, CFL says
Guardian Caps, a soft-shell helmet cover, among CFL's new player-safety initiatives
Guardian Caps: Why some NFL players are wearing them in training camps
EXPLAINER: NFL using helmet caps for player safety, research
Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN
NFL hopes to reduce head injuries with helmet experiment
NFL players wear Guardian Caps to reduce head trauma during training camp
Guardian Caps: Why some NFL players are wearing them in training camps