NFL players wear Guardian Caps to reduce head trauma during training camp
NFL May Allow Alternate Helmets In 2021 - CBS Boston
Guardian cap' to prevent head injuries mandated for practices, CFL says
NFL May Allow Alternate Helmets In 2021 - CBS Boston
Guardian cap' to prevent head injuries mandated for practices, CFL says
NFL training camps: Guardian Cap players are wearing over helmets, why
Puffy, spongy Guardian Caps could help curb NFL head injuries - The Washington Post
NFL executive hints that Guardian Caps could eventually be worn in games, along with position-specific helmets
Here's why some Patriots players are wearing caps over their helmets during training camp