As NFL mandates Guardian caps in practice, area high school football teams have been using them for years, Sports
NFL players don Guardian Caps, designed to protect from concussion
Guardian Cap Results: “Exceeded Our Expectations”
Guardian Caps, a soft-shell helmet cover, among CFL's new player-safety initiatives
Why are NFL players wearing padding on helmets at training camp?
KTTC In-Depth: Guardian Caps in high school football
What are those funny-looking soft caps on NFL helmets during camp?, Sports
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
Large Bubble Helmets Are Guardian Caps, NFL's New Safety Measure
NFL's use of Guardian padded helmet caps in camp draws support and skepticism - The Athletic
What are Guardian Caps and how are they helping football teams?
What are Guardian Caps? NFL's latest padded helmets for added safety
Jake Hanson on LinkedIn: NFL mandates special helmets for start of camp
High school football teams go soft in the fight against brain injuries