Could Guardian Caps be used during NFL games for player safety?, Pro Football Talk
The story behind those soft-shell puffy Guardian Caps players have been wearing
High school football looks to Guardian Cap for head safety
NFL executive hints that Guardian Caps could eventually be worn in games, along with position-specific helmets
NFL CMO Dr. Allen Sills explains importance of mandated guardian caps during training camp
Guardian Cap: What are and why the NFL asks this safety measure in helmets
Guardian Caps Guardian Sports
Guardian Caps leave some NFL players and coaches with concerns: 'You feel like a bobblehead'
NFL's use of Guardian padded helmet caps in camp draws support and skepticism - The Athletic
NFL players beginning to adopt protective Guardian Caps over helmets at practice - NBC Sports
Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN
More Guardian Caps, And '0' On The Field