NFL players wear Guardian Caps to reduce head trauma during training camp
NFL Makes Ruling On Players Wearing Guardian Cap During Game - The Spun: What's Trending In The Sports World Today
Why are NFL players wearing padding on helmets at training camp?
NFL hopes to reduce head injuries with helmet experiment
NFL players don Guardian Caps, designed to protect from concussion
Large Bubble Helmets Are Guardian Caps, NFL's New Safety Measure
Seeking to reduce head contact, NFL mandates use of Guardian Cap helmet for early portion of training camp - ESPN
Guardian cap' to prevent head injuries mandated for practices, CFL says
Could Guardian Caps be used in games? - NBC Sports
Guardian Caps: Why some NFL players are wearing them in training camps
NFL's use of Guardian padded helmet caps in camp draws support and skepticism - The Athletic
Puffy Guardian Caps Could Reduce NFL Player Concussions
Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN