NFL mandates use of Guardian Caps for training camp in 2022 - Cincy Jungle
NFL players don Guardian Caps, designed to protect from concussion
Guardian Caps debut at NFL training camps around the league
NFL executive hints that Guardian Caps could eventually be worn in games, along with position-specific helmets
What are Guardian Caps? NFL players sport specialty helmets for 2022 minicamp
What are NFL players wearing on their helmets at training camp and how do they work? - The Mirror US
Puffy, spongy Guardian Caps could help curb NFL head injuries - The Washington Post
Here's why some Patriots players are wearing caps over their helmets during training camp
Eagles players on Guardian Caps: 'We look a little goofy,' but all for safety
Why are NFL players wearing padding on helmets at training camp?