Guardian Cap Results: “Exceeded Our Expectations”
Guardian Caps: NFL requires use of helmet cover at training camps to reduce head injuries
Carolina Panthers - Wikipedia
Why are NFL players wearing padding on helmets at training camp?
Why are NFL players wearing padding on helmets at training camp?
Executive Hints Guardian Caps Could Eventually Be Worn In Games - RealGM Wiretap
NFL's use of Guardian padded helmet caps in camp draws support and skepticism - The Athletic
Funky-Looking Guardian Caps Rejected by NFL for Regulation Play, OK'd for Practice - Core77
EXPLAINER: NFL using helmet caps for player safety, research