NFL: Concussions dropped by more than 50% among players who wore Guardian Caps during summer
Guardian Cap: What are and why the NFL asks this safety measure in helmets
Helmets – The Concussion Blog
Guardian Cap debuts during minicamps in effort to reduce avoidable head contact
Puffy, spongy Guardian Caps could help curb NFL head injuries - The Washington Post
CFL introduces mandatory extra helmet protection for multiple positions. As well as other new health & safety measures. : r/sports
Eagles players on Guardian Caps: 'We look a little goofy,' but all for safety
Daily Slop - 22 Aug 23: Ravens are now the most recent NFL team to lose a preseason game; Washington at 2-0
Philadelphia Eagles: Jason Kelce has hilarious response to new safety measures
Guardian Caps: NFL Requires Use Of Helmet Cover At Training, 46% OFF
Damar Hamlin and Sam Peltzman: Where Football Meets Economics - Econlib