Funky-Looking Guardian Caps Rejected by NFL for Regulation Play, OK'd for Practice - Core77
Coverage of the NFL in Guardian Caps
What in the world are those weird-looking helmets the Saints are wearing in camp?, Rod Walker
The 2023 Uni Watch NFL Season Preview - by Paul Lukas
NFL expands rule against misuse of helmet; Guardian Caps required in regular season, postseason
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 Makes Ruling On Players Wearing Guardian Cap During Game - The Spun: What's Trending In The Sports World Today
NFL exec suggests Guardian Caps worn to protect players during practices could one day debut in games, National