As NFL mandates Guardian caps in practice, area high school football teams have been using them for years, Sports
With a little imagination NFL's new Guardian Caps take on different look in Cleveland: Crowquill
EXPLAINER: NFL using helmet caps for player safety, research
Padded helmet cover shows little protection for football players - Scope
Concussions: Can cap keep football players' heads in game? – Orange County Register
NFL hopes to reduce head injuries with helmet experiment
College football safety gets shaped by research, including possible head-hit counts
What Pros Wear: Guardian Caps What are Those Helmet Covers Being Worn in Practice? - What Pros Wear
NFL offseason priorities for 2023: Possible rules changes, safety reforms - ESPN
Florio PFT] The Guardian Cap apparently works. But if a player asks to wear it in a game, the league would say no. : r/nfl
New Football Helmet Could Save the Sport