Guardian Caps: NFL requires use of helmet cover at training camps to reduce head injuries
NFL's use of Guardian padded helmet caps in camp draws support and skepticism - The Athletic
Guardian Caps: What are they and why are NFL players wearing them? - Sactown Sports
Truth About Guardian Caps
NFL CMO Dr. Allen Sills explains importance of mandated guardian caps during training camp
Arizona Cardinals defensive end J.J. Watt not fan of the new league-mandated Guardian Caps on helmets
EXPLAINER: NFL using helmet caps for player safety, research
NFL executive hints that Guardian Caps could eventually be worn in games, along with position-specific helmets
Morse says 'Halo' helmets making a difference
What is a Guardian Cap? Meet the NFL's newest safety measure
GUARDIAN CAP DEBUTS AT TRAINING CAMPS LEAGUE-WIDE
Eagles players on Guardian Caps: 'We look a little goofy,' but all for safety
Guardian Caps debut at NFL training camps around the league
Guardian Caps, a soft-shell helmet cover, among CFL's new player-safety initiatives
NFL Mandates Guardian Caps During Training Camp - Team Insight