NFL's use of Guardian padded helmet caps in camp draws support and skepticism - The Athletic
Puffy Guardian Caps Could Reduce NFL Player Concussions
What's With Those Padded Caps NFL Players Are Wearing In Training Camp?
Guardian Sports - Frequently Asked Questions
Padded helmet cover shows little protection for football players - Scope
Puffy, spongy Guardian Caps could help curb NFL head injuries - The Washington Post
Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN
Guardian Caps debut at NFL training camps around the league
Guardian Caps leave some NFL players and coaches with concerns: 'You feel like a bobblehead'
Guardian Caps: The new helmets worn by several NFL teams
What Pros Wear: Guardian Caps What are Those Helmet Covers Being Worn in Practice? - What Pros Wear
Guardian Caps: Why some NFL players are wearing them in training camps