EXPLAINER: NFL using helmet caps for player safety, research
Morse says 'Halo' helmets making a difference
Guardian Caps', NFL's Most Recent Attempt At Preventing Head Injuries
NFL players wear Guardian Caps to reduce head trauma during
Padded helmet cover shows little protection for football players
Why are NFL players wearing padding on helmets at training camp?
What is a Guardian Cap? Meet the NFL's newest safety measure
NFL says Guardian Caps reduced concussions by more than 50%
Guardian Caps debut at NFL training camps around the league
Guardian Cap Debuts at Training Camps League-wide
NFL Guardian Caps: How Do They Work? – NBC 5 Dallas-Fort Worth