EXPLAINER: NFL using helmet caps for player safety, research
NFL's top doctor does not expect Guardian Caps to be worn in games - NBC Sports
Seahawks' Shelby Harris thinks NFL's new guardian caps are 'stupid' - Field Gulls
NFL expands rule against misuse of helmet; Guardian Caps required in regular season, postseason
Chiefs TE Travis Kelce thinks NFL's mandated 'Guardian Caps' are silly
U mad, bro?: Steelers fans simmer over stadium name, safety helmets, ESPN 'GOAT' list; Pirates fans fume about Hall of Fame
Guardian Cap debuts during minicamps in effort to reduce avoidable head contact
Jonathan Allen clearly isn't a fan of NFL's mandated safety helmets
Guardian Caps Exceed NFL's Expectations - Guardian Sports
Coverage of the NFL in Guardian Caps
Seattle Seahawks and Denver Broncos are going to Super Bowl XLVIII, Super Bowl XLVIII
What's with padded helmet caps teams are wearing
Puffy, spongy Guardian Caps could help curb NFL head injuries - The Washington Post