NFL reports reduction in concussions among players who wore Guardian Caps in preseason - The Athletic
Puffy, spongy Guardian Caps could help curb NFL head injuries - The Washington Post
Guardian Caps NFL: What player positions are required to wear them?
NFL to Expand Guardian Cap Wear in 2023 - Steelers Now
NFL expands rule against misuse of helmet; Guardian Caps required in regular season, postseason
NFL health and safety officials recommend expanded use of Guardian Caps in the summer, per report
Puffy, spongy Guardian Caps could help curb NFL head injuries - The Washington Post
Explanation: NFL using helmet caps for player safety, research
NFL Players Experiment With 'Guardian Caps' to Protect Heads – NBC Connecticut