NFL expands rule against misuse of helmet; Guardian Caps required in regular season, postseason
Santa Barbara Independent, 10/05/17 by SB Independent - Issuu
CFL introduces mandatory extra helmet protection for multiple positions. As well as other new health & safety measures. : r/sports
EXPLAINER: NFL using helmet caps for player safety, research
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
NFL hopes to reduce head injuries with helmet experiment
NFL executive hints that Guardian Caps could eventually be worn in games, along with position-specific helmets
Packers Practice Roundup - August 17, 2023 (2nd Patriots Joint Practice)
Why are NFL players wearing padding on helmets at training camp?
Football helmet - Wikipedia
Puffy, spongy Guardian Caps could help curb NFL head injuries - The Washington Post