NFL's top doctor does not expect Guardian Caps to be worn in games - NBC Sports
NFL executive hints that Guardian Caps could eventually be worn in games, along with position-specific helmets
NY Daily News Sports on Twitter: They're called Guardian Caps, and they're now mandatory for all 32 NFL teams through the second preseason game — the time when the league says head
NFL Guardian Caps: How Do They Work? – NBC Bay Area
Coverage of the NFL in Guardian Caps
Coverage of the NFL in Guardian Caps
Coverage of the NFL in Guardian Caps
Funky-Looking Guardian Caps Rejected by NFL for Regulation Play, OK'd for Practice - Core77
NFL Guardian Caps: How Do They Work? – NBC Bay Area