Here's why some Patriots players are wearing caps over their helmets during training camp
Tennessee football: UT Vols use Guardian helmet covers
As NFL mandates Guardian caps in practice, area high school football teams have been using them for years, Sports
Guardian Cap - Soft-Shell Protective Helmet Cover : Football Helmets : Sports & Outdoors
Packers share thoughts on wearing Guardian Caps at camp
Concussions among players who wore Guardian Caps over summer dropped more than 50%, NFL says - ESPN
NFL players experiment with 'Guardian Caps' to protect heads
NFL mandates use of Guardian Caps for training camp in 2022 - Cincy Jungle
What's with padded helmet caps teams are wearing
Padded helmet cover shows little protection for football players - Scope
Guardian Caps are the latest effort to address CTE, football concussion concerns