Guardian Caps: Why some NFL players are wearing them in training camps
Football helmets with outside padding get tryout at Bremerton High School
As NFL mandates Guardian caps in practice, area high school football teams have been using them for years, Sports
Puffy, spongy Guardian Caps could help curb NFL head injuries - The Washington Post
Packers share thoughts on wearing Guardian Caps at camp
More padding the issue of concussions and better helmets
Guardian Cap Debuts at Training Camps League-wide
Guardian Caps Guardian Sports
What are Guardian caps? See the NFL's latest head protection device - Deseret News
The impact of 'Guardian Caps' on player safety
NFL's use of Guardian padded helmet caps in camp draws support and skepticism - The Athletic