EXPLAINER: NFL using helmet caps for player safety, research
NFL hopes to reduce head injuries with helmet experiment - Wilmington News Journal
How New Helmet Technology Will Make the NFL and NHL Safer, News, Scores, Highlights, Stats, and Rumors
Helmet Innovation: Continued advancements to keep players safer
Large Bubble Helmets Are Guardian Caps, NFL's New Safety Measure
Helmet manufacturers work on safer youth equipment
Bellmore-Merrick athletics debuts new guardian caps, Herald Community Newspapers
What Does A Safety Do In Football? Explained – vIQtory Sports
This might be a dumb question, but why do they wear these extra pads on their helmets for camp but remove them for games? : r/KansasCityChiefs