NFL players wear Guardian Caps to reduce head trauma during
Reduces impact up to 33% One size fits all Insulates in hot & cold weather Fits both football and lacrosse helmets Connects to the facemask with 4
Guardian Protective Helmet Cover
NFL Players Experiment With 'Guardian Caps' to Protect Heads – NBC
Park High School football blazes safety trail with Guardian Caps
Guardian Caps: Why some NFL players are wearing them in training camps
Guardian Caps Guardian Sports
EXPLAINER: NFL using helmet caps for player safety, research
Guardian cap' to prevent head injuries mandated for practices, CFL
Why the Ticats are wearing those giant helmets at practice