Guardian Caps NFL: What player positions are required to wear them
NFL players experiment with 'Guardian Caps' to protect heads
Bellmore-Merrick athletics debuts new guardian caps
Can footballers wear a baseball cap during a match? - Premier
What is the Q Collar, the device NFL players are wearing around
EXPLAINER: NFL using helmet caps for player safety, research
ICYMI: Players all across the NFL are wearing Guardian Caps during
Seeking to reduce head contact, NFL mandates use of Guardian Cap