NFL makes Guardian Caps mandatory for many positions through second preseason game - NBC Sports
The Pat McAfee Show – Podcast – Podtail
Steelers mailbag: Is it really necessary to document every snap of the QB competition?
NFL players wear Guardian Caps to reduce head trauma during training camp
Guardian Cap Debuts at Training Camps League-wide
NFL's use of Guardian padded helmet caps in camp draws support and skepticism - The Athletic
Concussions among players who wore Guardian Caps over summer dropped more than 50%, NFL says - ESPN
Guardian Caps Debut at Training Camps Across the NFL
NFL Introduces Guardian Caps At First Week Of Training Camp - The Sports Credential
Cory's Corner: So Now What?
NFL players don Guardian Caps, designed to protect from concussion